Abstract
Vanadate glasses using $B_2O_3$ as a network former and with CuO additive were mainly investigated in relation to electrical properties. Crystalline phases formed by heat-treatment in each composition were examined and dc electrical conductivity changes of the glasses were analyzed. Crystalline phases were identified as $V_3O_5,\;a-CuV_2O_6\;and\;{\beta}-CuV_2O_6$ by XRD analysis. Crystallization degrees of $V_2O_5$ and ${\beta}-CuV_2O_6$ were little changed with heat-treatment time, but those of ${\alpha}u-CuV_2O_6$ were changed sharply with heat-treatment time. The more crystallization of ${\alpha}u-CuV_2O_6$ occurred, the higher electrical conductivity was observed. Electrical conductivities with $10^{-2}~10^{-4}/{\Omega}/cm$ at room temperature(303K) could be obtained by controlling the glass compositions. The electrical conductivities were increased with increasing of $V_20_5$ content and decreasing of alkality($CuO/B_2O_3$). In this study, electron was proved to be charge carrier by seebeck coefficient measurement. Accordingly, the glasses are believed to be n-type semiconductor. Calculated activation energies for the conduction were in the range 0.098-0.124 eV. Electrical conduction mechanism was small polaron hopping without showing variable range hopping in the temperature range $30~200^{\circ}C$.
유리 형성제로 $B_{2}O_{3}$를 사용하고 CuO를 첨가한 vanadate계 3성분계 유리의 전기적 특성을 조사하였다. 각 조성별 결정화온도에서 열처리 시간을 다르게 하여 생성되는 결정상을 조사 하였으며, 결정화 특성에 따른 직류 전기 전도도의 변화를 분헉하였다. 생성 결정물은 XRD 분석결과 $V_{2}O_{5},\;{\alpha}-CuV_{2}O_{6}$로 판명 되었으며, 열처리 시간에 따라 $V_{2}O_{5}\;와\;{\beta}-CuV_{2}O_6$의 결정화도는 별다른 변화가 없었으나 ${\alpha}-CuV_{2}O_{6}$의 결정화도는 크게 변화하였고 ${\alpha}-CuV_{2}O_{6}$의 결정화도 증가에 따라 전기 전도도가 증가 하였다. 전기 전도도는 상온(303K)에서 유리 조성을 변화시켜 $10^{-2}~-10^{-4}{\Omega}^{-1}cm^{-1}$ 범위로 조절될수 있었다. $V_{2}O_{5}$ 함량이 증가할수록, 염기도($CuO/B_{2}O_{3}$)가 감소할수록 전기 전도도가 증가 하였다. 이 유리의 charge carrier는 전자인 n-type 반도체임이 seebeck coefficient 측정결과 판명되었으며, 전자 전도에 대한 활성화 에너지는 0.098-0.124eV로 계산되어졌다. 측정 온도인 $30~200^{\circ}C$에서 small polaron hopping conduction이 발생함이 관찰되었고, variable range hopping은 보이지 않았다.
