烧结温度对CuAlO_2陶瓷电性能的影响
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摘要
为了提高CuAlO_2陶瓷的电导率,满足其在热电器件使用中的要求,以Cu_2O、Al_2O_3为原料,铝硅酸盐玻璃为添加剂,采用两步固相烧结法制备了CuAlO_2(CAO)陶瓷,研究烧结温度对CAO陶瓷电导率的影响.实验发现:随着烧结温度的上升,CAO陶瓷的密度、晶粒尺寸和电导率逐渐增大.烧结温度为1 175℃时,CAO陶瓷的表观密度和相对密度达到最大值,分别为4. 408 g/cm3和95. 8%.当烧结温度达1 200℃时,CAO陶瓷晶粒生长发育完整,呈现多边形结构,且其电导率达到最大(2. 42 S/m),比1 050℃的样品高了近10倍.阻抗谱分析表明,烧结温度对CAO陶瓷电导率的改善主要来自于晶粒阻抗的贡献.
To improve the conductivity of CuAlO_2 ceramics,it is necessary to meet the requirements of thermoelectric devices. The delafossite CuAlO_2( CAO) ceramics was made of Cu_2O, Al_2O_3 and aluminosilicate glass powder with traditional solid sintering method. The influence of sintering temperature on the conductivity of CAO ceramics with aluminum silicate glass was studied. Results show that the density,grain size and electrical conductivity of CAO ceramics increase gradually with increasing sintering temperature. The apparent density and relative density of CAO ceramics reach maximum,4. 408 g/cm3 and 95. 8%,respectively,when the sintering temperature is up to 1 175 ℃. When the sintering temperature comes up to 1 200 ℃,the grains of CAO ceramics develop fully and the shape of grains becomes polygon. The electrical conductivity reaches its maximum,2. 42 S/m,which increases by nearly 10 times as much compared with 1 050 ℃. The impedance spectrum analysis shows that with increasing sintering temperature,the improvement of the electrical conductivity of CAO ceramics is mainly due to the contribution of grain impedance.
To improve the conductivity of CuAlO_2 ceramics,it is necessary to meet the requirements of thermoelectric devices. The delafossite CuAlO_2( CAO) ceramics was made of Cu_2O, Al_2O_3 and aluminosilicate glass powder with traditional solid sintering method. The influence of sintering temperature on the conductivity of CAO ceramics with aluminum silicate glass was studied. Results show that the density,grain size and electrical conductivity of CAO ceramics increase gradually with increasing sintering temperature. The apparent density and relative density of CAO ceramics reach maximum,4. 408 g/cm3 and 95. 8%,respectively,when the sintering temperature is up to 1 175 ℃. When the sintering temperature comes up to 1 200 ℃,the grains of CAO ceramics develop fully and the shape of grains becomes polygon. The electrical conductivity reaches its maximum,2. 42 S/m,which increases by nearly 10 times as much compared with 1 050 ℃. The impedance spectrum analysis shows that with increasing sintering temperature,the improvement of the electrical conductivity of CAO ceramics is mainly due to the contribution of grain impedance.
引文
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[2] HICKS L D,DRESSELAUS M S. Effect of quantum-well structures on the thermoelectric figure of merit[J].Physical Review B,1993,47(19):12727.
[3] WANG Y,GONG H,ZHU F,et al. Optical and electrical properties of p-type transparent conducting Cu Al O2thin films prepared by plasma enhanced chemical vapor deposition[J]. Materials Science and Engineering B,2001,8(5):131-134.
[4] KOUMOTO K,KODUKA H. Thermoelectric properties of single crystal Cu Al O2with a layered structure[J]. Journal of Materials Chemistry,2001,11(2):251-252.
[5] KIZAKI H. First-principles materials design of Cu Al O2based dilute magnetic semicoriducting oxide[J]. Journal of Applied Physics,2005,4(4):38-42.
[6] KAWAZOE H,YANG H,KAZU U. Transparent p-type conducting oxides:design and fabrication of p-n heterojunctions[J]. MRS Bulletin,2000,25(8):28-36.
[7] SAKULKA A,SAKADA R. Power factor improvement of delafossite Cu Al O2by liquid-phase sintering with Ag2O addition[J]. Materials Science in Semiconductor Processing,2016,5(6):313-323.
[8] PARK K,KWON H C,NAHM S,et al. Improvement in thermoelectric properties of Cu Al O2by adding Fe2O3[J].Journal of Alloys and Compounds,2007,437(1/2):1-6.
[9] KINGERY W D. Densification during sintering in the presence of a liquid phase[J]. Journal of Applied Physics,1959,30(3):301-306.
[10] KANI K, TOSHINOBU Y Y, MIYAYI Y.Semiconducting glass-ceramics based on the Cu Al O2-Si O2system[J]. High Techology Ceramics,1987,3:297-307.
[11] LEE K R,LEE J H,YOO H I. Grain size effect on the electrical properties of nanocrystalline ceria[J]. Journal of the European Ceramic Society,2014,34(10):2363-2370.
[12] SEKULI D L,LAZAR Z Z,JOVALEKIC C D,et al.Impedance spectroscopy of nanocrystalline MgFe2O4and MnFe2O4ferrite ceramics:effect of grain boundaries on the electrical properties[J]. Science of Sintering,2016,48(1):17-28.
[13] GERHARDT R. Impedance and dielectric spectroscopy revisited:distinguishing localized relaxation from longrange conductivity[J]. Journal of Physics and Chemistry of Solids,1994,55(12):1491-1506.
[14] WANG Y,CHENG L,ZHU M K,et al. Investigation on microstructure and electrical properties of Cu Al1-xYxO2ceramics by electrical impedance spectroscopy[J].Journal of Alloys and Compounds,2016,654:455-459.
[15] HU B B,ZHU M K,GUO J J,et al. Origin of relaxor behavior in K1/2Bi1/2-Ti O3-Bi(Mg1/2Ti1/2)O3investigated by electrical impedance spectroscopy[J]. Journal of American Ceramic Society,2016,99(5):1637-1644.