Asada Akie

Noritomi Kazuo

English

Noritomi, Kazuo

Asada, Akie

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Studies on the Electrical Couductivity of a few Samples of Granite and Andesite

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Studies on the Electrical Couductivity of afew Samples of Granite and Andesite著者 Noritomi  Kazuo, Asada  Akie雑誌名 Science reports of the Tohoku University. Ser.5, Geophysics巻 7号 3ページ 201-207発行年 1956-03URL http://hdl.handle.net/10097/44549    Studies on the  Electrical Conductivity of a few Samples                  of Granite and Andesite                   By KAZUO  NORITOMI and  AI<IE  ASADA               Geophysical Institute, Faculty of Science, TOhoku University                           (Received 5 December 1955)                              Abstract          The measurements of the changein the electrical conductivity against he     temperature variance to the melting point of samples were carried out about a few     samples ofgranite and andesite.  According to the results of experiments, it was found that the change of     electrical conductivity with temperature would be devided into three or four processes,     that is, up to 500°C, from 500°C to 900°C, from 900°C to 1100°C and above 1100°C.           At lower temperatures, the activation energies of all samples wereofsmall     values and the changes of electrical conductivity with temperature were affectedmainly     by Fe203 and  Al203 contained in the samples. At high temperatures, it  seemed that     the phenomena were the same as that of silicate minerals. 1 Introduction    'With the progress of the theory of matters, a study of the electrical conductivity of rocks has been developed from the new standpoint. In order to investigate the properties of  materials in the interior of the earth, it is desirable to  make various investigations on the basic rocks constructing the crust of the earth. Recently, RUNCORN and TOZER [1] reported that the change of electrical conductivity of basic  minerals with temperature could be devided into three processes, viz, up to 600°C, from 600°C to 1100°C and. above  1100°C. Each process indicates respectively impurity semiconduction, intrinsic semiconduction and ionic conduction. The authors have been carrying out various experiments on the electrical properties of silicate minerals. [2] [3] [4]. In the present paper, the studies on the electrical conductivity of a few samples of grainte and andesite were reported.    The first purpose of this experiment was to measure the change of the electrical conductivity of these samples against he temperature variance to the melting point of samples, the second was to compare the results of these samples with each other for the same temperature range and to investigate what elements composing the samples play the main  role of charged carrier. 2 Method of the Experiment    In order to attain our object as mentioned above, we adopted the following method. A massive  salmple was ground into powder and stuffed between two con-202 K.  NORITOMI and A. ASADA        pot  „.,../  E  /,////  P1'1 A C  B                 //,' -• - . !: .>/i/ cizT 151 Tt1 .1:1_\  / , ,                          -. •••: -/ / \.., i                             . ,/ .-• ) •           , , ., • :'-' ////i R                        / ,//- 1;.: •-.. :,- '/  /                         '                     ,/, , Ill   //                                         .--0 EF./             0',V.'.1::...-r47//\. ____2                  /v. . 7.1/SSallipte                             .••                                                                               t-Gc4-r•uce                                                    E.F Etect-",••^                                             /.                y.'.:5•                        :..--:"'.:;./,/,'.-'E.Etectr''de5                     it.                       /-:„-.-.4..,..•...-••.....^'•///://1 ell   PotentI  0  Neter                    //:,.‘,/,` -Nr.,4re-..',','',„A.C.aAtternative  Li  rrent Brwse                             '::-'..-"-:>47,-,  "  - /,'  ,—• R.  Record of Temperature  and Res(-Stance                         Fig.  I. The equipment used in measurement. centric iron cylinders which function as the electrods. In this case, we determined the dimension of cylindrical electrods as the  •end effects were negligible. The equipment is shown in detail in Figure  1. The temperature of specimen was measured by use of the thermojunction, which was put in the inside electrode. With this equipment, the resistance of specimen were measured by using an A. C. bridge of 50 cycles.     In reality, it is desirable to meas- - 6 F-1-77,                  , , 1 1 s  , ure about the block sample instead of)---3 the powdered one, because the block  I  i  T  .__. and the powder indicated different  / conductivities with each other. How-  6                                                    . , ever, for example, in the case of a block of granite, the measurement  -s    .  was  disturbed by growth of cracks                                            'a within the sample at higher temper- Z' 1 •  , -  atures. Moreover, the representative  •  ,  ----#-- BLOCS  I--.----,—  Po  wde r phenomena may not be observable  3  .      on  account  ofirregular  distribution J  _rL   I   -  -  of rock-forming c ystals within thei  -2- sample.     On  the other hand, the  measure-ments for the block and the powder samples of quartz diorite were carried  :  out in order to estimate the differ-  5 6  7  8  9  /0  'I  I?  ,3  wi  0  16  '%                                                         VT ence of the electrical conductivity                                              Fig. 2. The electrical conductivities as a for the temperature change. Ac- function of reciprocal absolute temperature in cording to the results as seen in cases of the block and the powdered specimens                                            in quartz diorite. Figure 2, both cases indicated the      STUDIES ON THE  ELECTRICAL  CONDUCTIVITY OF A FEW SAMPLES 203 same relative changes with temperature, but for the absolute value of conductivity, the values of block samples showed  10,-402 times as large as those of the powdered. Therefore, it may  be concluded that the relative changes of the electrical conduc-tivities for the both cases of block and powder are equal at any temperatures. 3 Results of Experiment  The samples and their localities are as follows,        Quartz : Nishida village Fukushima Prefecture,  Japan.  Perthite  : Suisyoyama, Fukushima Prefecture, Japan.  Granite  1,2,3,  : Tanobata, North eastern parts of Iwaizumi Town, Iwate                  Prefecture,  Japan.  Andesite  : Fumoto,  Nishi-IVIonai Town, Hiraga District, Akita Prefecture,  Japan.    Table. 1. Chemical composition a d Norm. of the samples. Analyst: Y. UEDA * I. KATO)  GraniteGraniteGranite Quartz  Basaltic   ConstituentAndesite hypAugiteerthene       2 2 3 diorite  andesite                                                        andesite  Si0,  67.50  63.15 76.95 58.24 64.78 61.01 49.71  Al201 15.77 17.01  12.59 16.59 14.91 14.41  21.:0  Fe203 2.61  3,30 1.31 3.68 5.56 4.39 3 30  FeO 2.25 2.53 0.12 3.39 0.78 3.23 5.97  MgO 1.82 2.60 0.22 3.27 0.54 3.16 2.80  CaO 4.47 5.09 1.08 5.80 3.82 3.82 12.59  Na2O 1.99 1.59 1.02 3.97 4.62 3.28 1.58   K20 2.80 3.74 5.99 1.50 2.00 2.66 0.45  H20.4. 0.14 0.40 0,10 0.22 0.68 0.48 1.08  H2O_ 0.06 0.10 0.06 0.98 1.10 0.84 0.75  TiO2 0.25 0.41 - 1.50 0.82 0.19 0.73  P205 0.02 0.02 0.03 0.57 0.27 0.10 0.24  MnO 0.10  0.07 0.02  -  - - 0.20    Total  99,78 100.01 99.49 99.42 99.88 100.75 100.70    Quartz 31.86 24.36 45.42 14.82 22.80 18.00 7.50    Orthoclase 16.68 21.68 35.58 8.90 11.68 15.57 2.78    • Albite 16.77 13.62 8.38 34.60 39.30  27.77 13.10    Anorthite  22.24 25.30 5.56 32.80 13.90 16.68 49.76   Corundam 1.33 1.12 2.48  -  -- -  -   Diopside  _  - - 0.68 1.28 5.03 9.22  Hyperthene 6.71 7.82 0.60 7.25 0.02 6.59 9.82    Magnetite 3.71 4.87 0.23 5.34 0.23 6.50 4.87    Ilmenite 0.45 0.46 - 2.89 1.52 1.52 1.00   Hematite -  - 1.12 - 5.44  -  -  Normative  Ab„  Ab22  Ab56 Ab31  Ab„    Plagioclase  An„  An„  A  n44  An„ An40  An.,,  An„_,,       Augite hyperthene  Andesite  ; Mizusawa, Western parts of Niiyama,                 Yasawagi Village, Mogami District, Akita Prefecture,Japan.      Quartz  diorite  ; Upper stream of the Tsuchiuchi  River; Hagino Village,                 Mogami District, Yamagata Prefecture,  japan.  Basaltic  andesite : Mitaki,  Sendai, Miyagi Prefecture,  japan. The chemical and mineral compoistion of the granite and the andesite groups are shown in Table 1. The results obtained from the experiments for quartz, perthite and204 K. NORITOMI and A. ASADA  Jo a 1  —                                                                 ,-.9. ,-;                                                                                                                                                                                                     -4-, ,-'-'                                                                                                                                                                   •,--, g                                                                       • 0  ;, , • ,--, ,                                                                                                                                                                                                                                                      -4 ,   ' tr.) 0 bp                                                                                                                    • 1.)                                          —n-) ____    ,,r0g  0     cv rdU _ a)                                                                                                   C-ci bD                                                                                        4..)q) q) Qi                          ob. 3•3 4..) .4, c.) 'cI  .'                                                            Izst                                   Q.)Z..' 0.   cr)                                   (2)C1-. (.5 (5 (.. c.) u,                       1 :111 r\J                                                                    O 0                                                                                                        ,-g g                                                                                                                                               ..j•-.4-'-,0 0_x....±,,,                                                                                                                                      .-:-... g                                                                                             a> ,                                                                                            d           e. >\4:4„:41/4....,.......,4„..‹............ -4-,                                                                                             U                                                                                                                                                                                                           . .                                                                                              En ,               • 1>,,...,',,,,,,j......,,000                            X                                                                                                                                                            . ,        -NTIIA.. ,.--,          llo . "II CL) +)       1. )--i 03  bil4k.: " C.) ;--‘                         0 -.."Plia... ........ i Vji         . a)                                                                                               , ---..„-'--------___. o- co c--- .0                 'a) 7 ,-) N '77)                            I I ;DA 0  1 I .. C,i          ._0 CO 7 CIA                                                                  S4.5 >,                                                                                                                                                                                                     4-. 0 it .' - •--I • .                                                                                                                                                                                                                                                                                          -1-4   K   -.0 0 10    .'1')+12 40.                     0 u--)0fai                      —--.Q.,,,q)(1)—.                                        ..).4..)0  ,C1C.)0                                                                                                           ,--VI..-.'CI           111-.._'k)oi'-,c7419-,                          _oc:5b)t'D                                                                                                   -;                                                                                                     u--'5  ^ -.,,,r..___  in4-)CD                    •-.00-4 )      INL.._°—T1—.l'_,'*.--'.-''sa)'7,1                        'C'%3''T'D0                                                                                                                                        ro      -- _r\Ja)0                                                                                                               .4(73         O 1-            •0;\L,                                                                                                         .--..':,C.           o,,00    \1'".                                                                                                        4-,0ilik6- 1 11111%1141‘     ,c)d                                                                                               cn00 g CD-i                                                                                          0                      01111111N4444  .4 q)                 '\ .... CD Ct  ,  4•  .L.A.   'km. ---. -  CO ,0                                                                                                                                       ,...,         . H  en     O-     rt-----,t,      '1')--- 0                                ',-)a,\,  I  iI  bD  9  607 .. •CT,         STUDIES ON THE ELECTRICAL CONDUCTIVITY  OF A FEW SAMPLES 205          Table: 2. The values of  .6..E and  Cr, at the  different temperature ranges. The hatching            parts show the temperature region  in which the conductivity changes irregularly.                   The values of  AE are shown in the unite of eV,                    The values in the blacket show  low'.            400 500 600 700 800 900 1000  L100 1200                     (-0.37.51) E.:(828..28)5.5  Granite 1 (226) •        0.9 1.4 4.5       Granite 2  (-2.4)  (0.8) (165)  0.6 1.4 4.3 15.6       Granite 3  (-4.2) (0.8) (171) (610)  0.7.1-7.1.4-=. 1.6      Andesite(-2.2)  7-_  (1.1)  -  (48)  Augite 0.6  1.1  1.7 1.3 3.7 16.4        hyperthene  (-4 .3)  (-1.5) (56) (-0.4) (137) (606)  andesite    Quartz  0.8 0.9 1.6 8.0  diorite  (-2.7)  (-1,7) (71) (316)        (Powder)  Quartz 0.4{                 0.7 0.9 1.6 11.1          diorite       Block (-3.9) (-2) (-0.8) (67) (6.1)  ;       Basaltic 0.1  0.3 1.5 1.1 0.9  andesite  (-6.5)  (-4.0) (65) (4.3)  (-0.5)  ,     Quartz0.9 1.6 4.7 12.5  (-3 .6) (1.1) (173) (453)               1.3 1.6 0.7 5.6     Perthite (-0,6) (1.1) (-2.4) (201)   granite group are shown in Figure 3, and for andesite group in Figure 4. In the figures,   the ordinate and the abscissa demonstrate respectively logarithm of electrical con-  ductivity and reciprocal of the absolute temperature. As seen in Figures 3 and 4,   each curve consists of a few straight lines having the different gradients, which in-   creases with the rise  of temperature. Therefore, these curves are expressed by the   equation as follows  ;  LSE  AE2  -  cr  •-=  ci  e-  hT  +  Cr2  eYf  +    '    where  LIE activation energy and k  is  BOLTZMAN'S constant. The values of  a and  dE    for each sample are show in Table 2. As the values for  a are concerned with powder   samples, they are not always unique in the present case, but they may  be useful to   decide the approximate conditions of the samples.       From Figure 3, Figure 4 and Table 1, it may be said that the changes of the    electrical conductivity with temperature can be devided into three or four processes,  that is, up to 500°C, from 500°C to 900°C, from 900°C to 1100°C and above 1100°C.   Above 800°C, the processes for different rocks are similar to that for quartz. This fact   means that the phenomena in these temperature ranges are influenced mostly by silica   contained within the samples.  On the  other  hand,  at lower temperatures from 500°C206 K. NORITOMI and A.  ASA.DA  10,91,  do             -2 -a-r,-8 -10 -12        :,      8mil..     Mil        .111   6allpl                          0oaEii         .:...  ,11.    2..... __          0 • 0,2— 0.4 0.6 0.8 ' 1.0 12  AE (eV)               Fig. 5. The relations betweenthevaluesof  AE (and  o) and the                          temperature in the lower temperature region.  to 800°C the curves are  somewhat different from one another. These departures eem to depend upon the elements of  Fe203,  A1,03 and  FeO, especially of  Fe,,O, contained within the samples. For example, Figure 5 indicates the relation between  AE (and  (7) and the amount of  Fe,03 contained within the sample. But,  the result of basaltic  andesite is an exception of this relation. It may be caused by the character of the basic rock. A marked change is observed near the melting point of the samples and  no  considerable" change in the conductivity can be seen in the higher temperature  ranges above the melting point, up to about 1500°C. In general, the conductivity  of the melting sample seems to be not so much dependent upon temperature. Finally, in  the whole range of temperature, the changes in the electrical conductivity of most samples are similar to that of quartz. 4 Conclusion     The electrical  conductivities of the granitse and the andesite groups eem to depend  -upon that of silicate mineral. At lower  temperatures, however,  o- and  LIE of samples  depends upon  FeOz, and  Al203, that is, the process at lower temperatures i   com  sidered to be a sort of semiconduction caused by the element having relatively small  activation energy.     At high temperatures, the changes of the electrical conductivities of all samples  are nearly equal. This signifies that the phenomena in the samples containing  abundant silica are controlled by the properties of silica.     Near the melting point, remarkable changes are found in the conductivity of  samples.     In concluding this paper, the authors wish to express their thanks to Prof. Y.  KATO for his supervision and encouragement for this study. Their thanks and ack- nowledgements are due to Dr.  J. Kato and Assist. Prof. Y. Ueda for providing the      STUDIES ON THE ELECTRICAL CONDUCTIVITY OF A FEW SAMPLES 207 samples used in the study and for their valuable suggestion from the petrological point of view.                               References   1. RUNCORN, S.K. and Tozer, D.C.,  : The Eletrical Conductivity of Olivine at High      Temperatures and Pressures. Ann. de Geophys. 11,  98-102, (1955)   2.  NoRrromi,  K.  : Studies on the Change of Electrical Conductivity with Temperature of        a few Silicate Minerals.  ,Sei. Rep,  Tolioku Univ. Ser. 5, 6, 119-126, (1955).   3.  NoRrromi,  K. : Investigation of Thermoelectricity for Metallic and Silicate  Minerals.       ibid. 7, 94-101, (1955)   4.  NoRiTomt, K. and TAKAGI,  A.: A Note on the Electrical Polarization in Quartz and       Perthite.  ibid, 5, 183, (1953).

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Studies on the Electrical Couductivity of a few Samples of Granite and Andesite

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