Investigation of Change in Surface Area and Grain Size of Cadmium Titanate Nanofibers upon Annealing and Their Effect on Oxygen Sensing

Abstract

We have investigated the phase changes in CdTiO3 nanofibers as the annealing temperature of nanofibers was increased from 600 to 1200 °C. The nanofibers annealed at 600 °C were ilmenite with a very small amount of CdO. Upon annealing at 950 °C, CdO was completely removed. Annealing at 1000 °C yielded pure perovskite nanofibers, and at temperatures above 1100 °C rutile TiO2 nanofibers were obtained. Brunauer-Emmett-Teller (BET) analysis showed that with increase in annealing temperature the surface area of nanofibers was decreased. The nanofibers annealed at 600 °C have the higher surface area of ∼9.41 m(2)/g. Then oxygen sensors using CdTiO3 nanofibers annealed at 600 °C (ilmenite) and 1000 °C (perovskite) were fabricated. The sensitivity of the ilmenite nanofibers sensor was 2 times than that of the perovskite nanofibers sensor. The response and recovery times were 120 and 23 s, respectively, for the ilmenite nanofibers sensor, whereas response and recovery times were 156 and 50 s, respectively, for the perovskite nanofibers sensor. Better oxygen characteristics of ilmenite nanofibers are attributed to their large surface area and porosity. Therefore, we believe that ilmenite CdTiO3 nanofibers are potential candidates to develop practical oxygen sensors.

Comparison of different phases of bismuth silicate nanofibers for photodegradation of organic dyes

“…The nanofibers annealed at 600°C are of Bi 4 (SiO 4 ) 3 phase, as reported in a previous study are also presented in this manuscript for comparison (Batool et al 2014). However, the nanofibers annealed at 500°C have Bi 2 SiO 5 phase as shown in Fig.…”

“…If we further heat treat the nanofibers at 600°C, the crystalline peaks related to Bi 4 (SiO 4 ) 3 phase of the BS system with JCPDS Card No. 080-1596 has been observed (Batool et al 2014). The Bi 4 (SiO 4 ) 3 has cubic phase.…”

“…The Bi 4 (SiO 4 ) 3 has cubic phase. It also has few peaks of bismuth silicon oxide that can be removed by further heating the sample at higher temperatures (Imran et al 2014). Figure 1d shows the N 2 adsorption-desorption isotherms of Bi 4 (SiO 4 ) 3 and Bi 2 SiO 5 nanofibers.…”

“…where C 0 is a concentration of dye prior to photodegradation (mg/L), C t is the dye concentration at reaction time t for decolourization, and k app is the apparent rate constant (min -1 ) (Batool et al 2014). The apparent rate constant k app of the Bi 2 SiO 5 nanofibers and Bi 4 (SiO 4 ) 3 nanofibers for MO and SO dyes is found by fitting the experimental data (Fig.…”

Charge carrier transport mechanisms in perovskite CdTiO3 fibers

“…19 Titanium tetraisopropoxide (Ti(CH 3 ) 2 CHO) 4 >99%), Cadmium acetate (Cd(CH 3 COO) 2 · 2H 2 O>98%), ethanol (C 2 H 5 OH >98%), acetic acid (CH 3 COOH >98%), and polyvinyl-pyrrolidone (PVP) (M W = 13, 00 000) were purchased from Sigma Aldrich. All chemicals were used without any further purification and were of analytical grade.…”