Monte Carlo Simulations Applied To Alx Gay In1-x-y X Quaternary Alloys (x=as,p,n): A Comparative Study

We develop a different Monte Carlo approach applied to the Ax By C1-x-y D quaternary alloys. Combined with first-principles total-energy calculations, the thermodynamic properties of the (Al,Ga,In) X (X=As, P, or N) systems are obtained and a comparative study is developed in order to understand the roles of As, P, and N atoms as the anion X in the system Alx Gay In1-x-y X. Also, we study the thermodynamics of specific compositions in which AlGaInN, AlGaInP, and AlGaInAs are lattice matched, respectively, to the GaN, GaAs, and InP substrates. We verify that the tendency for phase separation is always towards the formation of an In-rich phase. For arsenides and phosphides this occurs in general for lower temperatures than for their usual growth temperatures. This makes these alloys very stable against phase separation. However, for nitrides the In and/or Al concentrations have to be limited in order to avoid the formation of In-rich clusters and, even for low concentrations of In and/or Al, we observe a tendency of composition fluctuations towards the clustering of the ternary GaInN. We suggest that this latter behavior can explain the formation of the InGaN-like nanoclusters recently observed in the AlGaInN quaternary alloys. © 2005 The American Physical Society.7120Stringfellow, G.B., (1983) J. Appl. Phys., 54, p. 404. , JAPIAU 0021-8979 10.1063/1.331719Olego, D., Chang, T.Y., Silberg, E., Caridi, E.A., Pinczuk, A., (1982) Appl. Phys. Lett., 41, p. 476. , APPLAB 0003-6951 10.1063/1.93537Fujii, T., Nakata, Y., Sigiyama, Y., Hiyiamizu, S., (1986) Jpn. J. Appl. Phys., Part 1, 25, p. 254. , JAPNDE 0021-4922Mowbray, D.J., Kowalski, O.P., Hopkinson, M., Skolnick, M.S., David, J.P.R., (1994) Appl. Phys. Lett., 65, p. 213. , APPLAB 0003-6951 10.1063/1.112676Chen, G.S., Wang, T.Y., Stringfellow, G.B., (1990) Appl. Phys. Lett., 56, p. 1463. , APPLAB 0003-6951 10.1063/1.102499Gavrilovic, P., Dabkowski, F.P., Meehan, K., Willians, J.E., Stutius, W., Hsieh, K.C., Holonyak, N., Mahajan, S., (1988) J. Cryst. Growth, 93, p. 426. , JCRGAE 0022-0248 10.1016/0022-0248(88)90563-5Tanaka, T., Yanagisawa, H., Kakibayashi, H., Minagawa, S., Kajimura, T., (1991) Appl. Phys. Lett., 59, p. 1943. , APPLAB 0003-6951 10.1063/1.106143Nakamura, S., (1999) Semicond. Sci. Technol., 14, p. 27. , SSTEET 0268-1242 10.1088/0268-1242/14/6/201Li, J., Nam, K.B., Kim, K.H., Lin, J.Y., Jiang, H.X., (2001) Appl. Phys. Lett., 78, p. 61. , APPLAB 0003-6951 10.1063/1.1331087Kneissl, M., Treat, D.W., Teepe, M., Miyashita, N., Johnson, N.M., (2003) Appl. Phys. Lett., 82, p. 2386. , APPLAB 0003-6951 10.1063/1.1568160Yasan, A., McClintock, R., Mayes, K., Darvish, S.R., Zhang, H., Kung, P., Razeghi, M., Han, J.Y., (2002) Appl. Phys. Lett., 81, p. 2151. , APPLAB 0003-6951 10.1063/1.1508414Nagahama, S., Yanamoto, T., Sano, M., Mukai, T., (2001) Jpn. J. Appl. Phys., Part 1, 40, p. 788. , JAPNDE 0021-4922Hirayama, H., Kinoshita, A., Yamabi, T., Enomoto, Y., Hirata, A., Araki, T., Nanishi, Y., Aoyagi, Y., (2002) Appl. Phys. Lett., 80, p. 207. , APPLAB 0003-6951 10.1063/1.1433162Chen, C.H., Chen, Y.F., Lan, Z.H., Chen, L.C., Chen, K.H., Jiang, H.X., Lin, J.Y., (2004) Appl. Phys. Lett., 84, p. 1480. , APPLAB 0003-6951 10.1063/1.1650549Feng, S.W., Cheng, Y.C., Chung, Y.Y., Yang, C.C., Ma, K.J., Yan, C.C., Hsu, C., Jiang, H.X., (2003) Appl. Phys. Lett., 82, p. 1377. , APPLAB 0003-6951 10.1063/1.1556965Ferreira, L.G., Wei, S.-H., Zunger, A., (1991) Int. J. Supercomput. Appl., 5, p. 34. , IJSAE9 0890-2720Zarkevich, N.A., Johnson, D.D., (2003) Phys. Rev. B, 67, p. 064104. , PRBMDO 0163-1829 10.1103/PhysRevB.67.064104Drautz, R., Singer, R., Fähnle, M., (2003) Phys. Rev. B, 67, p. 035418. , PRBMDO. 0163-1829. 10.1103/PhysRevB.67.035418Sanchez, J.M., Ducastelle, F., Gratias, D., (1984) Physica a, 128, p. 334. , PHYADX 0378-4371 10.1016/0378-4371(84)90096-7Marques, M., Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Furthmuller, J., Bechstedt, F., (2003) Appl. Phys. Lett., 83, p. 890. , APPLAB 0003-6951 10.1063/1.1597986Kresse, G., Furthmüller, J., (1996) Comput. Mater. Sci., 6, p. 15. , CMMSEM. 0927-0256. 10.1016/0927-0256(96)00008-0Kresse, G., Furthmüller, J., (1996) Phys. Rev. B, 54, p. 11169. , PRBMDO. 0163-1829. 10.1103/PhysRevB.54.11169Metropolis, N., Rosenbluth, A.W., Rosenbluth, M.N., Teller, A.H., Teller, E., (1953) J. Chem. Phys., 21, p. 1087. , JCPSA6 0021-9606 10.1063/1.1699114Hohenberg, P., Kohn, W., (1965) Phys. Rev., 136, p. 864. , PRVBAK 0096-8269 10.1103/PhysRev.136.B864Vanderbilt, D., (1990) Phys. Rev. B, 41, p. 7892. , PRBMDO 0163-1829 10.1103/PhysRevB.41.7892Perdew, J.P., Zunger, A., (1981) Phys. Rev. B, 23, p. 5048. , PRBMDO 0163-1829 10.1103/PhysRevB.23.5048Monkhorst, H.J., Pack, J.D., (1974) Phys. Rev. B, 13, p. 5188. , PLRBAQ 0556-2805 10.1103/PhysRevB.13.5188Vegard, L., (1921) Z. Phys., 5, p. 17. , ZEPYAA 0044-3328Cowley, J.M., (1950) J. Appl. Phys., 21, p. 24. , JAPIAU 0021-8979 10.1063/1.1699415Wei, S.-H., Ferreira, L.G., Bernard, J.E., Zunger, A., (1990) Phys. Rev. B, 42, p. 9622. , PRBMDO 0163-1829 10.1103/PhysRevB.42.9622Teles, L.K., Furthmüller, J., Scolfaro, L.M.R., Leite, J.R., Bechstedt, F., (2000) Phys. Rev. B, 62, p. 2475. , PRBMDO. 0163-1829. 10.1103/PhysRevB.62.2475Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Furthmller, J., Bechstedt, F., (2002) J. Appl. Phys., 92, p. 7109. , JAPIAU 0021-8979 10.1063/1.1518136Marques, M., Teles, L.K., Scolfaro, L.M.R., Ferreira, L.G., Leite, J.R., (2004) Phys. Rev. B, 70, p. 073202. , PRBMDO 0163-1829 10.1103/PhysRevB.70.073202Borroff, R., Merlin, R., Chin, A., Bhattacharya, P.K., (1988) Appl. Phys. Lett., 53, p. 1652. , APPLAB 0003-6951 10.1063/1.100441Ozoliņš, V., Wolverton, C., Zunger, A., (1998) Phys. Rev. B, 57, p. 6427. , PRBMDO 0163-1829 10.1103/PhysRevB.57.642

Theoretical Study Of Strain-induced Ordering In Cubic Inxga 1-xn Epitaxial Layers

Chemical ordering in cubic epitaxial InxGa1-xN layers is investigated by combining first-principles pseudo-potential plane-wave total-energy calculations, a local concentration-dependent cluster-based method, and Monte Carlo simulations. It is found that for the unstrained or fully relaxed layers there are no stable ordered structures, indicating the tendency of the alloy to undergo phase separation, in agreement with previous calculations and experiment. The energetics of the InxGal 1-xN layers pseudomorphycally grown on fully relaxed GaN (001) buffers shows that biaxial strain acts as the driving force for chemical ordering in the alloys. It is found that strained InxGa 1-xN alloy comprises stable ordered structures which are (210)-oriented super-lattices with composition in the range [0.5,0.63], the [AABB] alternation of planes (configuration "chalcopy-rite") being the most stable phase.69242453171-245317-10Nakamura, S., Fasol, G., (1997) The Blue Laser Diode, , Springer, BerlinAmbacher, O., (1998) J. Phys. D, 31, p. 2653Pearton, S.J., Zolper, J.C., Shul, R.J., Ren, F., (1999) J. Appl. Phys., 86, p. 1Kung, P., Razeghi, M., (2000) Opto-Electron. Rev., 8, p. 201(1991) Data in Science and Technology: Semiconductors, , edited by O. Madelung (Springer-Verlag, Berlin)Davydov, V.Yu., Klochikhin, A.A., Seisyan, R.P., Emtsev, V.V., Ivanov, S.V., Bechstedt, F., Furthmüller, J., Graul, J., (2002) Phys. Status Solidi B, 229, pp. R1Wu, J., Walukiewicz, W., Yu, K.M., Ager III, J.W., Haller, E.E., Lu, H., Schaff, W.J., Nanishi, Y., (2002) Appl. Phys. Lett., 80, p. 3967Chichibu, S., Azuhata, T., Sota, T., Nakamura, S., (1996) Appl. Phys. Lett., 69, p. 4188(1997) Appl. Phys. Lett., 70, p. 2822O'Donnell, K.P., Martin, R.W., Middleton, P.G., (1999) Phys. Rev. Lett., 82, p. 237Wetzel, C., Takeuchi, T., Amano, H., Akasaki, I., (1999) J. Appl. Phys., 85, p. 3786Chichibu, S.F., Abare, A.C., Mack, M.P., Minsky, M.S., Deguchi, T., Cohen, D., Kozodoy, P., Nakamura, S., (1999) Mater. Sci. Eng., B, 59, p. 298Lemos, V., Silveira, E., Leite, J.R., Tabata, A., Trentin, R., Scolfaro, L.M.R., Frey, T., Lischka, K., (2000) Phys. Rev. Lett., 84, p. 3666Krestnikov, I.L., Ledentsov, N.N., Hoffmann, A., Bimberg, D., Sakharov, A.V., Lundin, W.V., Tsatsul'Nikov, A.F., Gerthsen, D., (2002) Phys. Rev. B, 66, p. 155310Husberg, O., Khartchenko, A., As, D.J., Vogelsang, H., Frey, T., Schikora, D., Lischka, K., Leite, J.R., (2001) Appl. Phys. Lett., 79, p. 1243Behbehani, M.K., Piner, E.L., Liu, S.X., El-Masry, N.A., Bedair, S.M., (1999) Appl. Phys. Lett., 75, p. 2202Yamaguchi, S., Kariya, M., Nitta, S., Kato, H., Takeuchi, T., Wetzel, C., Amano, H., Akasaki, I., (1998) J. Cryst. Growth, 195, p. 309Teles, L.K., Furthmüller, J., Scolfaro, L.M.R., Leite, J.R., Bechstedt, F., (2000) Phys. Rev. B, 62, p. 2475Tabata, A., Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Kharchenko, A., Frey, T., As, D.J., Bechstedt, F., (2002) Appl. Phys. Lett., 80, p. 769Singh, R., Doppalapudi, D., Moustakas, T.D., Romano, L.T., (1997) Appl. Phys. Lett., 70, p. 1089Doppalapudi, D., Basu, S.N., Ludwig Jr., K.F., Moustakas, T.D., (1998) J. Appl. Phys., 84, p. 1389Ruterana, P., Nouet, G., Van Der Stricht, W., Moerman, I., Considine, L., (1998) Appl. Phys. Lett., 72, p. 1742Northrup, E., Romano, L.T., Neugebauer, J., (1999) Appl. Phys. Lett., 74, p. 2319Srivastava, G.P., Martins, J.L., Zunger, A., (1985) Phys. Rev. B, 31, pp. R2561Ferreira, L.G., Wei, S.-H., Zunger, A., (1991) Int. J. Supercomput. Appl., 5, p. 34Wei, S.-H., Ferreira, L.G., Zunger, A., (1992) Phys. Rev. B, 45, p. 2533Zunger, A., (1994) Handbook of Crystal Growth, 3, p. 998. , D. T. J. Hurle, Elsevier, AmsterdamTeles, L.K., Ferreira, L.G., Leite, J.R., Scolfaro, L.M.R., Kharchenko, A., Husberg, O., As, D.J., Lischka, K., (2003) Appl. Phys. Lett., 82, p. 4274Sanchez, J.M., Ducastelle, F., Gratias, D., (1984) Physica A, 128, p. 334Ozoliņš, V., Wolverton, C., Zunger, A., (1998) Phys. Rev. B, 57, p. 6427Lu, Z.W., Wei, S.-H., Zunger, A., Frota-Pessoa, S., Ferreira, L.G., (1991) Phys. Rev. B, 44, p. 512De Fontaine, D., (1979) Solid State Physics, 34, p. 73. , edited by H. Ehrenreich, F. Seitz, and D. Turnbull (Academic, New York)Connolly, J.W.D., Williams, A.R., (1983) Phys. Rev. B, 27, p. 5169Ferreira, L.G., Wei, S.-H., Zunger, A., (1989) Phys. Rev. B, 40, p. 3197Mbaye, A.A., Ferreira, L.G., Zunger, A., (1987) Phys. Rev. Lett., 58, p. 49Ferreira, L.G., Mbaye, A.A., Zunger, A., (1988) Phys. Rev. B, 37, pp. 10 547Ferreira, L.G., Ozoliņš, V., Zunger, A., (1999) Phys. Rev. B, 60, p. 1687Hohenberg, P., Kohn, W., (1964) Phys. Rev., 136, pp. B864Kohn, W., Sham, L.J., (1965) Phys. Rev., 140, pp. A1133Vanderbilt, D., (1990) Phys. Rev. B, 41, p. 7892Großner, U., Furthmüller, J., Bechstedt, F., (1998) Phys. Rev. B, 58, pp. R1722Großner, U., Furthmüller, J., Bechstedt, F., (1999) Appl. Phys. Lett., 74, p. 3851Perdew, J.P., Zunger, A., (1981) Phys. Rev. B, 23, p. 5048Monkhorst, H.J., Pack, J.D., (1976) Phys. Rev. B, 13, p. 5188Kresse, G., Furthmüller, J., (1996) Phys. Rev. B, 54, pp. 11 169Kresse, G., Furthmüller, J., (1996) Comput. Mater. Sci., 6, p. 15Metropolis, N., Rosenbluth, A.W., Rosenbluth, M.N., Teller, A.H., Teller, E., (1953) J. Chem. Phys., 21, p. 1087Zunger, A., (1987) Appl. Phys. Lett., 50, p. 164Neugebauer, J., Van De Walle, C.G., (1995) Phys. Rev. B, 51, pp. 10 568Scolfaro, L.M.R., (2002) Phys. Status Solidi A, 190, p. 15Silveira, E., Tabata, A., Leite, J.R., Trentin, R., Lemos, V., Frey, T., As, D.J., Lischka, K., (1999) Appl. Phys. Lett., 75, p. 3602Saito, T., Arakawa, Y., (1999) Phys. Rev. B, 60, p. 1701Takayama, T., Yuri, M., Itoh, K., Baba, T., Harris Jr., J.S., (2000) J. Appl. Phys., 88, p. 1104Karpov, Yu.S., (1998) MRS Internet J. Nitride Semicond. Res., 3, p. 16Shimotomai, M., Yoshikawa, A., (1998) Appl. Phys. Lett., 73, p. 325

Microscopic Description Of The Phase Separation Process In Al Xgayin1-x-yn Quaternary Alloys

Ab initio total energy electronic structure calculations are combined with Monte Carlo simulations to study the thermodynamic properties of Al xGayIn1-x-yN quaternary alloys. We provide a microscopic description of the phase separation process by analyzing the thermodynamic behavior of the different atoms with respect to the temperature and cation contents. We obtained, at growth temperatures, the range of compositions for the stable and unstable phases. The presence of Al in InGaN is proven to "catalyze" the phase separation process for the formation of the In-rich phase. Based on our results, we propose that the ultraviolet emission currently seen in samples containing AlInGaN quaternaries arises from the matrix of a random alloy, in which composition fluctuations toward InGaN- and AlGaN-like alloys formation may be present, and that a coexisting emission in the green-blue region results from the In-rich segregated clusters.707732021-073202-4Lemos, V., Silveira, E., Leite, J.R., Tabata, A., Trentin, R., Scolfaro, L.M.R., Frey, T., Lischka, K., (2000) Phys. Rev. Lett., 84, p. 3666. , and references thereinKung, P., Razegui, M., (2000) Opto-Electron. Rev., 8, p. 201Kneissl, M., Treat, D.W., Teepe, M., Miyashita, N., Johnson, N.M., (2003) Appl. Phys. Lett., 82, p. 2386Adivarahan, V., Chitnis, A., Zhang, J.P., Shatalov, M., Yang, J.W., Simin, G., Khan, M.A., Shur, M.S., (2001) Appl. Phys. Lett., 79, p. 4240Yasan, A., McClintock, R., Mayes, K., Darvish, S.R., Zhang, H., Kung, P., Razeghi, M., Han, J.Y., (2002) Appl. Phys. Lett., 81, p. 2151Nagahama, S., Yanamoto, T., Sano, M., Mukai, T., (2001) Jpn. J. Appl. Phys., Part 2, 40, pp. L778Teles, L.K., Furthmüller, J., Scolfaro, L.M.R., Leite, J.R., Bechstedt, F., (2000) Phys. Rev. B, 62, p. 2475Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Furthmüller, J., Bechstedt, F., (2002) J. Appl. Phys., 92, p. 7109Tamulaitis, G., Kazlauskas, K., Jursenas, S., Zukauskas, A., Khan, M.A., Yang, J.W., Zhang, J., Gaska, R., (2000) Appl. Phys. Lett., 77, p. 2136Hirayama, H., Kinoshita, A., Yamabi, T., Enomoto, Y., Hirata, A., Araki, T., Nanishi, Y., Aoyagi, Y., (2002) Appl. Phys. Lett., 80, p. 207Chen, C.H., Chen, Y.F., Lan, Z.H., Chen, L.C., Chen, K.H., Jiang, H.X., Lin, J.Y., (2004) Appl. Phys. Lett., 84, p. 1480Feng, S.W., Cheng, Y.C., Chung, Y.Y., Yang, C.C., Ma, K.J., Yan, C.C., Hsu, C., Jiang, H.X., (2003) Appl. Phys. Lett., 82, p. 1377Yamaguchi, S., Kariya, M., Nitta, S., Kato, H., Takeuchi, T., Wetzel, C., Amano, H., Akasaki, I., (1998) J. Cryst. Growth, 195, p. 309Takayama, T., Yuri, M., Itoh, K., Harris Jr., J.S., (2001) J. Appl. Phys., 90, p. 2358Matsuoka, T., (1998) MRS Internet J. Nitride Semicond. Res., 3, p. 54Marques, M., Teles, L.K., Ferreira, L.G., Scolfaro, L.M.R., Leite, J.R., unpublishedKresse, G., Furthmüller, J., (1996) Comput. Mater. Sci., 6, p. 15Marques, M., Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Furthmüller, J., Bechstedt, F., (2003) Appl. Phys. Lett., 83, p. 890Ferreira, L.G., Wei, S.-H., Zunger, A., (1991) Int. J. Opt. Sens., 5, p. 34Metropolis, N., Rosenbluth, A.W., Rosenbluth, M.N., Teller, A.H., Teller, E., (1953) J. Chem. Phys., 21, p. 1087Cowley, J.M., (1950) J. Appl. Phys., 21, p. 2

Estudo do comportamento ao fogo dos CFRP’s – sistemas passivos de proteção

Com o aumento da utilização dos materiais compósitos (FRP) são inevitavelmente encontrados novos problemas e desafios. De entre esses problemas, existem preocupações legítimas em relação ao seu comportamento quando expostos ao fogo. No caso de exposição direta ao fogo, é recomendável que os FRP sejam aplicados com medidas adicionais de prevenção. É objetivo deste trabalho estudar o comportamento dos materiais compósitos à base de fibras de carbono (CFRP) ao fogo. Os materiais utilizados foram a manta e o laminado de fibra de carbono. Para tal é apresentada uma campanha de ensaios com amostras de provetes de betão de dimensão 100×100×40 mm. O CFRP é colado na superfície dos provetes com resina epoxídica exposta à ação térmica. As medidas passivas estudadas neste trabalho são destinadas a impedir a ignição do fogo e a diminuir o impacto dos incêndios através de mecanismos que não necessitam de intervenção humana ou automatismos. Dependendo do tempo desejado para a resistência ao fogo, podem aplicar-se diversos materiais de proteção, no nosso estudo foi analisados o gesso cartonado e tintas intumescentes. A superfície reforçada é exposta à ação de dois fluxos de calor por radiação, 35 kW/m2 e 75 kW/m2, provenientes de um calorímetro de perda de massa. A evolução da temperatura é avaliada através de termopares colocados entre as superfícies de ambos os materiais permitindo uma análise da influência destes materiais de proteção na capacidade de reforço estrutural dos CFRP quando submetidos a temperaturas elevadas. Após os ensaios conclui-se que a placa de gesso tem um melhor desempenho quer para a manta quer para o laminado do que a tinta intumescente.info:eu-repo/semantics/publishedVersio

CFRP fire behaviour - passive protection system

The technique of reinforcing concrete structures by means of bonding composite fibre reinforced polymers (FRP) has been applied in the construction industry. There are several examples of application of these materials in bridges and in buildings, both in new construction and rehabilitation and/or strengthening of damaged structures. With the increasing use of FRP new problems and challenges are inevitably found. Among these subjects, there are legitimate concerns about the behaviour of FRP materials when exposed to fire action. It is the aim of this work to analyse the behaviour of composite materials exposed to fire, in particular composite materials based on carbon fibres (CFRP). Therefore a set of tests on 100 × 100 × 40 mm concrete specimens with CFRP are to be analysed using the test method recommended by EN ISO 13927. The CFRP sheet is glued on the top surface of the specimens using epoxy resin and exposed to thermal action. The surface of the reinforcement system is exposed to the action of different radiative heat fluxes, from 35 kW/m2 to 75 kW/m2, from a cone calorimeter and changes in temperature are determined by thermocouples placed between the surfaces of both materials, and the material heat release rate by the use of a thermopile. The influence of passive fire protection systems on the CFRP fire reaction is analysed considering different fire protection materials (gypsum boards, ceramic fibre sheets and intumescing paints). The temperature variation during the period of thermal exposure is measured across the surface of the different material layers, allowing to assess the influence of these fire protection materials to the CFRP structural reinforcement capabilities at elevated temperatures.The authors wish to acknowledge Reconco Company for the supply of plasterboard.info:eu-repo/semantics/publishedVersio

Statistical Model Applied To Ax By C1-x-y D Quaternary Alloys: Bond Lengths And Energy Gaps Of Alx Gay In1-x-y X (x=as, P, Or N) Systems

We extend the generalized quasichemical approach (GQCA) to describe the Ax By C1-x-y D quaternary alloys in the zinc-blende structure. Combining this model with ab initio ultrasoft pseudopotential calculations within density functional theory, the structural and electronic properties of Alx Gay In1-x-y X (X=As, P, or N) quaternary alloys are obtained, taking into account the disorder and composition effects. Results for the bond lengths show that the variation with the compositions is approximately linear and also does not deviate very much from the value of the corresponding binary compounds. The maximum variation observed amounts to 3.6% for the In-N bond length. For the variation of band gap, we obtain a bowing parameter b=0.26 eV for the (Ga0.47 In0.53 As)z (Al0.48 In0.52 As)1-z quaternary alloy lattice matched to InP, in very good agreement with experimental data. In the case of AlGaInN, we compare our results for the band gap to data for the wurtzite phase. We also obtained a good agreement despite all evidences for cluster formation in this alloy. Finally, a bowing parameter of 0.22 eV is obtained for zinc-blende AlGaInN lattice matched with GaN. © 2006 The American Physical Society.7323Li, J., Nam, K.B., Kim, K.H., Lin, J.Y., Jiang, H.X., (2001) Appl. Phys. Lett., 78, p. 61. , APPLAB 0003-6951 10.1063/1.1331087Adivarahan, V., Chitnis, A., Zhang, J.P., Shatalov, M., Yang, J.W., Simin, G., Asif Khan, M., Shur, M.S., (2001) Appl. Phys. Lett., 79, p. 4240. , APPLAB 0003-6951 10.1063/1.1425453Yasan, A., McClintock, R., Mayes, K., Darvish, S.R., Kung, P., Razegui, M., (2002) Appl. Phys. Lett., 81, p. 801. , APPLAB 0003-6951 10.1063/1.1497709Nagahama, S., Yanamoto, T., Sano, M., Mukai, T., (2001) Jpn. J. Appl. Phys., Part 1, 40, p. 788. , JAPNDE 0021-4922 10.1143/JJAP.40.L788Fujii, T., Nakata, Y., Sigiyama, Y., Hiyiamizu, S., (1986) Jpn. J. Appl. Phys., 25, p. 254. , JAPLD8 0021-4922Olego, D., Chang, T.Y., Silberg, E., Caridi, E.A., Pinczuk, A., (1982) Appl. Phys. Lett., 41, p. 476. , APPLAB 0003-6951 10.1063/1.93537Hirayama, H., Kinoshita, A., Yamabi, T., Enomoto, Y., Hirata, A., Araki, T., Nanishi, Y., Aoyagi, Y., (2002) Appl. Phys. Lett., 80, p. 207. , APPLAB 0003-6951 10.1063/1.1433162Takayama, T., Yuri, M., Itoh, K., Baba, T., Harris Jr., J.S., (2001) J. Cryst. Growth, 222, p. 29. , JCRGAE 0022-0248 10.1016/S0022-0248(00)00869-1Koukitu, A., Kumegai, Y., Seki, H., (2000) J. Cryst. Growth, 221, p. 743. , JCRGAE 0022-0248Feng, S.-W., Cheng, Y.-C., Chung, Y.-Y., Yang, C.C., Ma, K.-J., Yan, C.-C., Hsu, C., Jiang, H.X., (2003) Appl. Phys. Lett., 82, p. 1377. , APPLAB 0003-6951 10.1063/1.1556965Chen, C.H., Chen, Y.F., Lan, Z.H., Chen, L.C., Chen, K.H., Jiang, H.X., Lin, J.Y., (2004) Appl. Phys. Lett., 84, p. 1480. , APPLAB 0003-6951 10.1063/1.1650549Marques, M., Teles, L.K., Scolfaro, L.M.R., Ferreira, L.G., Leite, J.R., (2004) Phys. Rev. B, 70, p. 073202. , PRBMDO 0163-1829 10.1103/PhysRevB.70.073202Marques, M., Ferreira, L.G., Teles, L.K., Scolfaro, L.M.R., (2005) Phys. Rev. B, 71, p. 205204. , PRBMDO 0163-1829 10.1103/PhysRevB.71.205204Teles, L.K., Furthmüller, J., Scolfaro, L.M.R., Leite, J.R., Bechstedt, F., (2000) Phys. Rev. B, 62, p. 2475. , PRBMDO. 0163-1829. 10.1103/PhysRevB.62.2475Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Furthmüller, J., Bechstedt, F., (2002) J. Appl. Phys., 92, p. 7109. , JAPIAU. 0021-8979. 10.1063/1.1518136Teles, L.K., Furthmüller, J., Scolfaro, L.M.R., Leite, J.R., Bechstedt, F., (2001) Phys. Rev. B, 63, p. 085204. , PRBMDO. 0163-1829. 10.1103/PhysRevB.63.085204Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Furthmüller, J., Bechstedt, F., (2002) Appl. Phys. Lett., 80, p. 1177. , APPLAB. 0003-6951. 10.1063/1.1450261Tabata, A., Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Kharchenko, A., Frey, T., As, D.J., Bechstedt, F., (2002) Appl. Phys. Lett., 80, p. 769. , APPLAB. 0003-6951. 10.1063/1.1436270Connolly, J.W.D., Williams, A.R., (1983) Phys. Rev. B, 27, p. 5169. , PRBMDO 0163-1829 10.1103/PhysRevB.27.5169Chen, A.-B., Sher, A., (1995) Semiconductor Alloys, , Plenum Press, New YorkKresse, G., Furthmüller, J., (1996) Comput. Mater. Sci., 6, p. 15. , CMMSEM. 0927-0256. 10.1016/0927-0256(96)00008-0Kresse, G., Furthmüller, J., (1996) Phys. Rev. B, 54, p. 11169. , PRBMDO. 0163-1829. 10.1103/PhysRevB.54.11169Hohenberg, P., Kohn, W., (1964) Phys. Rev., 136, p. 864. , PRVBAK 0096-8269 10.1103/PhysRev.136.B864Kohn, W., Sham, L.J., (1965) Phys. Rev., 140, p. 1133. , PRVAAH 0096-8250 10.1103/PhysRev.140.A1133Vanderbilt, D., (1990) Phys. Rev. B, 41, p. 7892. , PRBMDO 0163-1829 10.1103/PhysRevB.41.7892Perdew, J.P., Zunger, A., (1981) Phys. Rev. B, 23, p. 5048. , PRBMDO 0163-1829 10.1103/PhysRevB.23.5048Monkhorst, H.J., Pack, J.D., (1976) Phys. Rev. B, 13, p. 5188. , PLRBAQ 0556-2805 10.1103/PhysRevB.13.5188Marques, M., Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Furthmüller, J., Bechstedt, F., (2003) Appl. Phys. Lett., 83, p. 890. , APPLAB. 0003-6951. 10.1063/1.1597986Jeffs, N.J., Blant, A.V., Cheng, T.S., Foxon, C.T., Bailey, C., Harrison, P.G., Mosselmans, J.F.W., Dent, A.J., (1998) Mater. Res. Soc. Symp. Proc., 512, p. 519. , MRSPDH 0272-9172Miyano, K.E., Woicik, J.C., Robins, L.H., Bouldin, C.E., Wickenden, D.K., (1997) Appl. Phys. Lett., 70, p. 2108. , APPLAB 0003-6951 10.1063/1.118963Saito, T., Arakawa, Y., (1999) Phys. Rev. B, 60, p. 1701. , PRBMDO 0163-1829 10.1103/PhysRevB.60.1701Sze, S.M., (1981) Physics of Semiconductor Devices, , Wiley, New YorkChen, S.-G., Fan, X.-Q., (1997) J. Phys.: Condens. Matter, 9, p. 3151. , JCOMEL 0953-8984 10.1088/0953-8984/9/15/008Sökeland, F., Rohlfing, M., Krüger, P., Pollmann, J., (2003) Phys. Rev. B, 68, p. 075203. , PRBMDO. 0163-1829. 10.1103/PhysRevB.68.075203Schörmann, J., Potthast, S., Schnietz, M., Li, S.F., As, D.J., Lischka, K., Phys. Status Solidi C, , ZZZZZZ. 1610-1634 (to be published)Yu. Davydov, V., Klochikhin, A.A., Seisyan, R.P., Emtsev, V.V., Ivanov, S.V., Bechstedt, F., Furthmüller, J., Graul, J., (2002) Phys. Status Solidi B, 229, p. 1. , PSSBBD. 0370-1972. 10.1002/1521-3951(200202)229:33.0.CO;2-OYu. Davydov, V., Klochikhin, A.A., Emtsev, V.V., Kurdyukov, D.A., Ivanov, S.V., Vekshin, V.A., Bechstedt, F., Haller, E.E., (2002) Phys. Status Solidi B, 234, p. 787. , PSSBBD. 0370-1972. 10.1002/1521-3951(200212)234:33.0.CO;2-HBechstedt, F., Furthmüller, J., Ferhat, M., Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Yu. Davydov, V., Goldhahn, R., (2003) Phys. Status Solidi a, 195, p. 628. , PSSABA. 0031-8965. 10.1002/pssa.200306164(1998) Gallium Nitride (GaN) I and II, Semiconductors and Semimetals, 50. , edited by J. I. Pankove and T. D. Moustakas, Vol. Academic Press, New York(1999), 57. , ibid. Vol. Academic Press, New YorkNadja, S.P., Kean, A.H., Dawson, M.D., Duggan, G., (1995) J. Appl. Phys., 77, p. 3412. , JAPIAU 0021-8979 10.1063/1.358631McIntosh, F.G., Boutros, K.S., Roberts, J.C., Bedair, S.M., Piner, E.L., El-Masry, N.A., (1996) Appl. Phys. Lett., 68, p. 40. , APPLAB 0003-6951 10.1063/1.116749Ryu, M.-Y., Chen, C.Q., Kuokstis, E., Yang, J.W., Simin, G., Khan, M.A., W. Yu, S.P., (2002) Appl. Phys. Lett., 80, p. 3943. , APPLAB 0003-6951 10.1063/1.1482415Yamaguchi, S., Kariya, M., Nitta, S., Kato, H., Takeuchi, T., Wetzel, C., Amano, H., Akasaki, I., (1998) J. Cryst. Growth, 195, p. 309. , JCRGAE 0022-0248 10.1016/S0022-0248(98)00629-0Davies, J.I., Marshall, A.C., Scott, M.D., Griffiths, R.J.M., (1988) Appl. Phys. Lett., 53, p. 276. , APPLAB 0003-6951 10.1063/1.100593Kopf, R.F., Wei, H.P., Perley, A.P., Livescu, G., (1992) Appl. Phys. Lett., 60, p. 2386. , APPLAB 0003-6951 10.1063/1.107005Cury, L.A., Beerens, J., Praseuth, J.P., (1993) Appl. Phys. Lett., 63, p. 1804. , APPLAB 0003-6951 10.1063/1.110668Böhrer, J., Krost, A., Bimberg, D.B., (1993) Appl. Phys. Lett., 63, p. 1918. , APPLAB. 0003-6951. 10.1063/1.110648Fan, J.C., Chen, Y.F., (1996) J. Appl. Phys., 80, p. 1239. , JAPIAU 0021-8979 10.1063/1.362862Vurgaftman, I., Meyer, J.R., Ram-Mohan, L.R., (2001) J. Appl. Phys., 89, p. 5815. , JAPIAU 0021-8979 10.1063/1.1368156Han, J., Figiel, J.J., Petersen, G.A., Myers, S.M., Crawford, M.H., Banas, M.A., (2000) Jpn. J. Appl. Phys., Part 1, 39, p. 2372. , JAPNDE 0021-4922 10.1143/JJAP.39.2372Aumer, M.E., Leboeuf, S.F., McIntosh, F.G., Bedair, S.M., (1999) Appl. Phys. Lett., 75, p. 3315. , APPLAB 0003-6951 10.1063/1.12533

Fire behaviour of ecological soil–cement blocks with waste incorporation: experimental and numerical analysis

The main goal of this study is to assess the behaviour of soil–cement blocks with incorporation of organic wastes. The problem of waste accumulation exists worldwide and has become a concern in today’s society, leading to enormous environmental damage. One of the possibilities for reducing their environmental impact is the reuse of these wastes in new materials. However, incorporating waste changes the mechanical, physical and thermal properties of the new material. In order to evaluate the potential use of waste in blocks composition, laboratory tests were conducted and the results were analysed. This article presents the fire behaviour of ecological soil–cement blocks with waste incorporation. Therefore, an experimental programme was performed using samples of wall panel with soil–cement blocks. The wall specimen under fire conditions was also analysed by a non-linear transient finite element numerical model, in time and temperature domains, and the numerical and experimental temperature fields were comparedinfo:eu-repo/semantics/publishedVersio

Evaluating the fire behaviour of cement-based lightweight materials with textile waste incorporation using a cone calorimeter

The conscientious utilization of natural resources and the efficient waste management have become a matter of great concern in recent years due to the harmful impacts on the environment. The construction sector presents itself as one of the sectors that most contributes to raw materials consumption and waste generation, demanding the investigation of more sustainable and ecofriendly building materials, where the valorisation of wastes originated from other industries can be promising. Following the sustainability concept in construction materials, this work investigates the potential use of textile waste in cement-based lightweight construction material, evaluating the fire reaction of the material using the cone calorimeter equipment. The samples were tested at three different radiant heat fluxes (35 kW/m2, 50 kW/m2, 75 kW/m2) to simulate different fire situations. For the highest heat flux, the lightweight construction element with textile waste incorporation showed a Heat Release Rate Average ≤ 18 kW/m2, a peak Heat Release Rate Average ≤ 60 kW/m2, and a Total Heat Release Average ≤ 33 MJ/m2. These results reveal a very satisfactory fire behaviour compared to other materials and show the suitability of using textile waste as lightweight cement-based materials.info:eu-repo/semantics/publishedVersio

Fire behaviour of wood and wood-based composite panels towards the development of fire-resistant multilayer systems

The use of sustainable natural resources has been practiced by the construction sector as a means to reduce energy demand and increase the efficiency of buildings. In this sense, wood and wood-based materials are alternative and renewable material sources that can be effectively used in building elements, such as doors and partition walls, which are required to provide adequate thermal, acoustic, and fire resistance performance. Such elements play an important role in the fire compartmentation of buildings. Appropriate selection of materials with a reduced potential of ignition and enhanced fire behaviour may reduce the heat flux, and the passage of hot gases and smoke, thus minimizing fire hazards. In the case of wood products, the combustibility of wood usually limits its use in fire-resistant components. However, the fire performance of wooden assemblies can be improved by using engineered wood products and insulation materials, which can be assembled into multilayer systems. This work investigates the performance of wood and wood-based multilayer panels exposed to ISO 834 standard fire curve to improve the knowledge about their fire resistance in terms of insulation (I) and integrity (E) criteria. The study considers pinewood, OSB (oriented strand board), and moisture-resistant MDF (medium-density fibreboard) of different thicknesses.info:eu-repo/semantics/publishedVersio

CFRP passive fire protection systems

An experimental programme was performed in order to evaluate the behaviour of composite materials when exposed to fire, in particular composite materials based on carbon fibres (CFRP). Therefore, a campaign of tests on concrete specimens with 100×100×40 mm was developed. The CFRP sheet is bonded on the surface of the specimens using epoxy resin and exposed to thermal action. The influence of passive protection systems on the burning behaviour of CFRP is analysed using different fire protection materials, such as gypsum plasterboard and intumescent paint. The surface of the reinforcement system is exposed to the action of different radiant fluxes equal to 35 kW/m2 and 75 kW/m2, from a cone calorimeter. The temperature evolution is determined by thermocouples placed between the concrete surface and CFRP, allowing to analyse the influence of these protective materials in the structural reinforcement capabilities of the CFRP when subjected to high temperatures.info:eu-repo/semantics/publishedVersio