Magnetic And Dielectric Proprieties Of Multiferroic (1-x)pb(fe 2/3w 1/3)o 3-xpbtio 3 Ceramics Prepared Via A Modified Two-stage Solid-state Reaction

Multiferroic Pb(Fe 2/3W 1/3)O 3-PbTiO 3 (PFW-PT) ceramics were synthesized via a modified two-stage solid-state reaction. This method utilized Fe 2WO 6, prepared at a first-stage, which was subsequently reacted with a stoichiometric amount of PbO and TiO 2 at the second stage. This procedure efficiently suppressed the formation of lead tungstates and leads to getting dense ceramics. Electric and dielectric properties of (1-x)Pb(Fe 2/3W 1/3)O 3-xPbTiO 3 solid solutions were investigated as a function of the frequency and temperature. All samples present density higher than 96% of the theoretical one, low percentage of pyrochlore phase (<2%) and relatively high electrical resistivity (>10 10 Ω.m). RF dielectric measurements over the temperature showed the presence of a peak, which is related to the ferro-paraelectric phase transition and conductive contributions (in the range 200-700 K), associated to a electronic hoping mechanism. The dielectric properties of the PFW shows a typical relaxor behaviour for x = 0 and 0.10 with frequency-dependent peak temperature (Tm), while the samples with higher PT-content undergo a 'normal' para-ferroelectric transition at the Curie temperature T C.The FE phase transition of PFW is shifted to higher temperatures by PbTiO 3 (PT) additions and high resistivity are obtained for PT containing samples. Different types of magnetic activity dependent on composition and temperature were found.144434441Ivanov, S.A., Eriksson, S.-G., Tellgren, R., Rundlof, H., Neutron powder diffraction study of the magnetoelectric relaxor Pb(Fe 2/3W 1/3)O 3 (2004) Materials Research Bulletin, 39 (14-15), pp. 2317-2328. , DOI 10.1016/j.materresbull.2004.07.025, PII S0025540804002260Mitoseriu, L., Vilarinho, P.M., Viviani, M., Baptista, J.L., Structural study of Pb(Fe 2/3W 1/3)O 3-PbTiO 3 system (2002) Materials Letters, 57 (3), pp. 609-614. , DOI 10.1016/S0167-577X(02)00839-X, PII S0167577X0200839XHong, C.-S., Chu, S.-Y., Li, B.-J., Su, W.-C., Chang, R.-C., Nien, H.-H., Investigation of the dielectric properties of MnO-additive Pb (Fe 2/3W 1/3) - PbTiO 3 relaxors using the spin-glass model (2008) Journal of Applied Physics, 103, pp. 094102-094108. , http://dx.doi.org/10.1063/1.2903511Liou, Y.-C., Effect of heating rate on properties of Pb (Fe 1/2Nb 1/2) O 3 ceramics produced by simplified wolframite route (2004) Ceramics International, 30, pp. 567-569. , http://dx.doi.org/10.1016/j.ceramint.2003.09.008Fiebig, M., Revival of the magnetoelectric effect (2005) Journal of Physics D: Applied Physics, 38, pp. 123-152. , http://dx.doi.org/10.1088/0022-3727/38/8/R01Mitoseriu, L., Stancu, A., Fedor, C., Vilarinho, P.M., Analysis of the composition-induced transition from relaxor to ferroelectric state in PbFe2/3W1/3O3-PbTiO3 solid solutions (2003) Journal of Applied Physics, 94, pp. 1918-1925. , http://dx.doi.org/10.1063/1.1586470Ivanov, S.A., Structural, magnetic and Mossbauer spectroscopic investigations (2007) Solid State Sciences, 9, pp. 440-450. , http://dx.doi.org/10.1016/j.solidstatesciences.2007.03.018Mitoseriu, L., Marré, D., Siri, A.S., Nanni, P., Magnetic properties of PbFe 2/3W 1/3O 3-PbTiO 3 solid solutions (2003) Applied Physics Letters, 83, pp. 5509-5511. , http://dx.doi.org/10.1063/1.1632033Feng, L., Guo, H., Ye, Z.-G., Magnetic ordering in relaxor ferroelectric (1 - x)Pb(Fe 2/3 W 1/3)O 3-xPbTiO 3 single crystals (2007) Journal of Materials Research, 22 (8), pp. 2116-2124. , DOI 10.1557/jmr.2007.0265Lu, C.H., Shinokasi, K., Mizutani, N., Kato, M., Liquid-phase formation in reaction process of 3PbO. Fe 2O 3. WO 3 (1989) Journal of the Ceramic Society of Japan, 97, pp. 97115-97120Mizutani Nobuyasu, Lu Chung-Hsin, Shinozaki Kazuo, Kato Masanori, Formation of a high-temperature liquid phase during the sintering of PbFe 2/3W 1/3O 3 (1990) Journal of the American Ceramic Society, 73 (5), pp. 1214-1220Khim, A.S., Wang, J., Wan, D., Li, L., Xue, J., Mechanical activation-assisted synthesis of Pb (Fe 2/3W 1/3) O 3 (2000) Journal of the American Ceramic Society, 83 (7), pp. 1575-1580Kong, L.B., Zhang, T.S., Ma, J., Boey, F., Progress in synthesis of ferroelectric ceramic materials via high-energy mechanochemical technique (2008) Progress in Materials Science, 53 (2), pp. 207-322. , DOI 10.1016/j.pmatsci.2007.05.001, PII S0079642507000266Khim, A.S., Wang, J., Junmin, X., Seeding effect in the formation of Pb (Fe 2/3W 1/3) O 3 via mechanical activation of mixed oxides (2000) Solid State Ionics, 132, pp. 55-61Khim, A.S., Junmin, X., Wang, J., Pb (Fe 2/3W 1/3) O 3 by mechanical activation of coprecipitated PbO, Fe 2O 3 and WO 3 (2002) Journal of Alloys and Compounds, 343, pp. 156-116Swartz, S.L., Shrout, T.R., Dielectric properties of pyrochlore lead magnesium niobate (1982) Materials Research Bulletin, 17 (10), pp. 1245-1250. , DOI 10.1016/0025-5408(82)90159-3Pinheiro, J.M.V., Mascarenhas, Y.P., Dois programas computacionais úteis em difratometria de raios-x por amostras policristalinas (1985) Anais Da 37 a Reunião Anual da SBPC, , Belo Horizonte. SBPC1985Chung-Hsin, L., Yeak-Chong, W., Fabrication of ferroelectric lead iron tungstate ceramics via a two-stage solid-state reaction (1995) Ceramics International, 21, pp. 413-419. , http://dx.doi.org/10.1016/0272-8842(02)72884-NKingery, W.D., Narasimhan, M.D., Densification during sintering in the presence of a liquid phase. II. Experimental (1959) Journal of Applied Physics, 30, pp. 307-310. , http://dx.doi.org/10.1063/1.1735156Fang, B., Sun, R., Shan, Y., Tezuka, K., Imoto, H., On the feasibility of synthesizing complex perovskite ferroelectric ceramics via a B-site oxide mixing route (2007) Journal of Materials Science, 42 (22), pp. 9227-9233. , DOI 10.1007/s10853-007-1908-zSzwagierczak, D., Kulawik, J., Influence of MnO 2 and Co 3O 4 dopants on dielectric properties of Pb(Fe 2/3W 1/3)O 3 ceramics (2005) Journal of the European Ceramic Society, 25 (9), pp. 1657-1662. , DOI 10.1016/j.jeurceramsoc.2004.05.022, PII S0955221904002584Feng, L., Ye, Z.G., Phase diagram and phase transitions in the relaxor ferroelectric Pb (Fe 2/3W 1/3) O 3-PbTiO 3 system (2002) Journal of Solid State Chemistry, 163, pp. 484-490. , http://dx.doi.org/10.1006/jssc.2001.9433Zhou, L., Vilarinho, P.M., Baptista, J.L., Ordering in lead iron tungstate relaxor ceramics (1998) Journal of the European Ceramic Society, 18 (10), pp. 1383-1387. , PII S0955221998000259Raymond, O., Font, R., Portelles, J., Suárez-Almodovar, N., Siqueiros, J.M., Frequency-temperature response of ferroelectromagnetic Pb (Fe 1/2Nb 1/2) O 3 ceramics obtained by different precursors. III. Dielectric relaxation near the transition temperature (2006) Journal of Applied Physics, 99, pp. 1241011-1241019. , http://dx.doi.org/10.1063/1.2201853Isupov, V.A., Peculiarities of the PbB 2/3 2+B 1/3 6+O 3 perovskites (2005) Ferroelectrics, 315, pp. 149-116. , http://dx.doi.org/10.1080/00150190490891463Bokov, A.A., Lattice site ion ordering effect on properties of Pb 2b'b" O 6 type triple oxides (1983) Fizika Tverdogo Tela, 25, pp. 2025-202

Essential oils in the diet of young bulls: Effect on animal temperament.

Plant extracts and essential oils can be alternative products to antibiotics, because several plants produce secondary metabolites with antimicrobial properties. Additionally, they may act on the olfactory system, which sends signals to the central nervous system releasing endorphins that may affect the feeling of an animal''s welfare while altering an animal''s temperament. This study was conducted to evaluate the animal temperament of 40 young crossbred bulls (one-half Brown Swiss and one-half Nellore) 10 ± 2.2 mo old with an average BW of 219 ± 11.7 kg. Young bulls were randomly assigned to 1 of 5 diets: control, which had no clove or cinnamon; clove leaf included to supply 3, 500 mg/animal per day; clove leaf included to supply 7, 000 mg/animal per day; essential oil of leaf cinnamon to supply 3, 500 mg/animal per day; or essential oil of leaf cinnamon to supply 7, 000 mg/animal per day. The animal temperament was evaluated by calculating the chute score, exit score, and temperament score for periods (each 28 d during 6 periods) and among diets. The data were submitted to an ANOVA using GLM procedures with SAS version 9.0. The diet and period were considered fixed effects, whereas the animals were considered a random effect. Differences between means were evaluated using a Tukey test of 5% of significance. The addition of clove or cinnamon essential oils did not alter (P > 0.05) animal temperament. The analysis of temperament score (P = 0.55), chute score (P = 0.71), and exit score (P = 0.06) did not show significant differences among the diets. The exit score was similar among the 6 periods (1.57, 1.80, 2.98, 2.02, 2.73, and 2.66, respectively); however, chute score and temperament score were greater (P < 0.001) in the first period compared with other periods. The values for chute score were 1.85, 1.40, 1.35, 1.33, 1.20, 1.17, respectively, and the values for temperament score were 2.31, 1.81, 1.67, 1.69, 1.50, and 1.56, respectively, for periods 1 to 6. The results of this study suggest that clove and cinnamon essential oils can be added as an additive in high-grain finished diets without changing the animal temperament

Investigation of microwave dielectric relaxation process in the antiferroelectric phase of NaNbO3 ceramics

This letter reports microwave dielectric measurements performed in the antiferroelectric phase of NaNbO3 ceramics from 100 to 450 K. Remarkable dielectric relaxations were found within the antiferroelectric phase and in the vicinity of ferroelectric-antiferroelectric phase transition. Such dielectric relaxation process was associated with relaxations of polar nanoregions with strong relaxor-like characteristic. In addition, the microwave dielectric measurements also revealed an unexpected and unusual anomaly in the relaxation strength, which was related to a disruption of the antiferroelectric order induced by a possible AFE-AFE phase transition.Comment: 4 pages and 4 figures - Paper accepted for publication in the Solid State Communication

Variação espacial de cátions, ânions e variáveis físico-químicas no rio Solimões-Amazonas entre Manaus e Jutaí, bacia amazônica

C&#225;tions e &#226;nions majorit&#225;rios s&#227;o esp&#233;cies qu&#237;micas de grande import&#226;ncia nos diversos compartimentos aqu&#225;ticos, por&#233;m, pouco abordados de forma exclusiva na bacia amaz&#244;nica. Neste sentido, o objetivo deste estudo foi avaliar a din&#226;mica espacial de Na+, Ca2+, K+, Mg2+, Cl- e SO4 2- em um trecho do rio Solim&#245;es-Amazonas, levando-se em considera&#231;&#227;o a alcalinidade, potencial hidrogeni&#244;nico (pH), condutividade el&#233;trica (CE), s&#243;lidos totais em suspens&#227;o (STS) e carbono org&#226;nico total (COT). As coletas foram realizadas em maio, julho e setembro de 2012 em sete pontos na calha principal do rio Solim&#245;es-Amazonas e na foz de alguns dos principais tribut&#225;rios: rios Juta&#237;, Juru&#225;, Japur&#225; e Purus. Os c&#225;tions e &#226;nions foram analisados por cromatografia de &#237;ons, STS por gravimetria, pH por potenciometria, alcalinidade por titula&#231;&#227;o potenciom&#233;trica, CE por condutimetria e o COT por oxida&#231;&#227;o catal&#237;tica por combust&#227;o. As concentra&#231;&#245;es m&#233;dias dos c&#225;tions seguiram esta ordem Ca2+>Na+>Mg2+>K+ e dos &#226;nions SO4 2->Cl-. De montante &#224; jusante a tend&#234;ncia foi diminui&#231;&#227;o nas concentra&#231;&#245;es de c&#225;tions e &#226;nions, das vari&#225;veis pH, CE, STS e alcalinidade, al&#233;m do aumento das concentra&#231;&#245;es de COT. O presente estudo evidenciou mudan&#231;as nas caracter&#237;sticas qu&#237;micas sofridas pelo rio Solim&#245;es em seu curso. O aporte dos tribut&#225;rios pode ser apontado como um dos fatores respons&#225;veis por essas modifica&#231;&#245;es