Malaysian Journal of Analytical Sciences Vol 24 No 5 (2020): 757 - 765

 

 

 

 

EQUIVALENT CIRCUIT ANALYSIS OF LaZrTa₃O₁₁ CERAMIC SYNTHESISED BY USING THE CONVENTIONAL SOLID-STATE METHOD

 

(Analisis Litar Sepadan Seramik LaZrTa₃O₁₁ Disintesis dengan Menggunakan Kaedah Keadaan Pepejal Konvensional)

 

Fadhlina Che Ros* and Jumiah Hassan

 

Physics Department, Centre for Defence Foundation Studies,

Universiti Pertahanan Nasional Malaysia, Kem Sungai Besi 57000, Kuala Lumpur, Malaysia

 

^*Corresponding author:  fadhlina@upnm.edu.my

 

 

Received: 13 November 2019; Accepted: 3 September 2020; Published:  12 October 2020

 

 

Abstract

LaZrTa₃O₁₁ ceramic with α-U₃O₈-type structure has been prepared by using the conventional solid state-route and studied by using powder X-ray diffraction for phase analysis and impedance spectroscopy for electrical measurements. It has hexagonal unit cell with space group P6₃22 at room temperature. LaZrTa₃O₁₁ is reported to be isostructural with CaTa₄O₁₁ and Ag₂Nb₄O₁₁; the structure is related to U₃O₈-structure, where it consists of single layers of edge-sharing pentagonal Ta-O bipyramids alternating with layers of edge-sharing octahedra. The impedance spectroscopy response showed that LaZrTa₃O₁₁ exhibited a typical insulating behaviour at room temperature, with permittivity, ε ~ 19. It was a highly resistive material with R >> 10⁹ Ω at temperature below 500^o C and as the temperature increased, frequency-dependence of alternating current conductivities at high frequency was clearly visible. The electrical properties of LaZrTa₃O₁₁ is best modelled by using non-Debye response circuit that consists of a parallel combination of a resistor, capacitor, and a constant phase element. 

 

Keywords:  LaZrTa₃O₁₁, dielectrics, high-temperature ceramics, lanthanide-oxide, non-Debye circuit   

 

Abstrak

Seramik LaZrTa₃O₁₁ dengan struktur jenis α-U₃O₈ telah disediakan melalui kaedah keadaan pepejal konvensional dan dikaji dengan menggunakan pembelauan sinar-X untuk analisis fasa dan spektroskopi impedans untuk kajian sifat keelektrikan. Ia mempunyai sel unit heksagonal dengan kumpulan ruang P6₃22 pada suhu bilik. LaZrTa₃O₁₁ dilaporkan mempunyai sama struktur dengan CaTa₄O₁₁ dan Ag₂Nb₄O₁₁; struktur tersebut adalah berkait dengan struktur U₃O₈ di mana ia terdiri daripada satu lapisan pentagonal bypiramid Ta-O berkongsi-sisi, berselang-seli dengan lapisan-lapisan oktahedra yang berkongsi-sisi. Tindak-balas spektroskopi impedans menunjukkan bahawa seramik LaZrTa₃O₁₁ mempamerkan sifat penebat yang tipikal pada suhu bilik, dengan kebolehtelapan, ε ~ 19. Ia adalah bahan berkerintangan tinggi dengan R >> 10⁹ Ω pada suhu di bawah 500^o C dan apabila suhu meningkat, kebergantungan frekuensi konduktiviti arus ulang alik pada frekuensi tinggi jelas kelihatan. Model terbaik sifat keelektrikan bagi seramik LaZrTa₃O₁₁ adalah menggunakan litar non-Debye yang terdiri daripada kombinasi selari perintang, kapasitor dan elemen fasa pemalar.

  

Kata kunci:  LaZrTa₃O₁₁, dielektrik, seramik bersuhu tinggi, oksida lanthanid, litar non-Debye

 

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