Phase transition monitoring and temperature sensing via FIR technology in Bi/Sm‐codoped KNN transparent ceramics

Abstract

The phase transition temperature (e.g., that of orthorhombic‐tetragonal TO‐T) of relaxor ferroelectrics are commonly obtained through electrical method (i.e., temperature dependence of dielectric constant), and the samples need to be coated with metal electrode and tested by a sophisticated impedance analyzer. This contact measuring method is inefficient, inconvenient and easy to damage the sample surface, inapplicable to transparent ferroelectrics. Here, we successfully fabricated Bi/Sm co‐doped K0.5Na0.5NbO3 transparent ceramics with photoluminescent behavior and relaxor‐like ferroelectricity, which simultaneously realized TO‐T monitoring and temperature sensing via fluorescence intensity ratio (FIR) technology. This simple, rapid, noncontact and nondestructive optical way displays small TO‐T deviation (merely 0.78%) compared to the electrical method. And the temperature‐dependent optical characteristics and coercive electric field all present abrupt changes, whose abnormal temperature regions are in accordance with that around TO‐T. In addition, the maximum absolute sensitivity and relative sensitivity of the ceramics reach 0.0072 K−1 (at 533 K) and 0.0111 K−1 (at 453 K), respectively, exhibiting superior optical temperature sensing performance. The tactical use of FIR technology is of great significance for widening the applications of luminescent‐ferroelectric transparent ceramics.

Superior Energy Storage Capability and Fluorescence Negative Thermal Expansion of NaNbO3‐Based Transparent Ceramics by Synergistic Optimization

“…Figure 9e shows the relative sensitivities of the ceramic with x = 0.03 as a function of temperature. The maximum S r value is 2.693% K −1 (at 233 K), which is competitive compared to previously reported materials, [14,15,28,[55][56][57][58][59][60] and demonstrates potential application in optical temperature sensing. Here, to explain the phenomenon of fluorescence negative thermal expansion, the energy transfer process between sensitizer (Yb 3+ ) and activator (Tm 3+ ) needs to be further analyzed.…”

“…The FIR fitting regression coefficient is shown in Figure 9e, and the COD(R 2 ) value is greater than 99%, proving high adaptability. To better estimate the optical sensing performance, the relative sensitivity (S r ) can be obtained by the following formula: [15] S r =…”

“…[13] High sensitivity and noncontact fluorescence intensity ratio (FIR) technology for accurate monitoring of TPC temperature is an effective strategy to eliminate overheating damage. [14,15] In theory, it is possible to achieve TPCs with excellent performance. For example, by doping non-equivalent ions to modulate the microstructure of dielectric ceramics (e.g., reducing grain size to nanoscale and elevating the density), it is hopeful that the dual effect of high breakdown electric field (E b ) and excellent transparency can simultaneously achieve.…”

High energy storage density achieved in BNT‐based ferroelectric translucent ceramics under low electric fields

“…To further investigate the impact of the BZT content on the crystal structure of (1−x)BNT−xBZT:0.6%Er 3+ ceramics, the magnification of the diffraction peak in the range of 44 to the substitution of Ba 2+ (1.61 Å) for Na + (1.39 Å), Bi 3+ (1.38 Å) in the A-site, and Zr 4+ (0.72 Å) for Ti 4+ (0.605 Å) in the B-site. 11,[27][28][29][30][31] Figure 3 presents the surface microscopic morphologies of (1−x)BNT−xBZT:0.6%Er 3+ ceramics. The average grain size, experimental densities (ρ m ), theoretical density (ρ th ), and relative densities (ρ r ) with content x are also displayed in Table 1.…”