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Lead-free KNN-based ceramics for electrocaloric and pyroelectric applications.

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Title: Lead-free KNN-based ceramics for electrocaloric and pyroelectric applications.
Authors: Chaliha, Chiranjit1 (AUTHOR) chiranjitchaliha969@gmail.com, Singh, Haobam Samananda1 (AUTHOR), Kumar, Parveen2 (AUTHOR), Maisnam, Mamata1 (AUTHOR)
Source: Ceramics International. Apr2026:Part B, Vol. 52 Issue 10, p14706-14722. 17p.
Subjects: Lead-free ceramics, Pyroelectricity, Energy harvesting, Dielectric properties, Ferroelectricity, Refrigeration & refrigerating machinery
Abstract: Lead-free, multifunctional ceramics with excellent electrocaloric and pyroelectric performance at low electric fields are required for long-term solid-state cooling and energy harvesting applications. This work created (1-x) K 0.47 Na 0.47 Li 0.06 Nb 0.98 Ta 0.02 O 3 + (x) Bi 0.5 Na 0.5 ZrO 3 ceramics using a two-step low-temperature method to reduce alkali volatilization and increase densification. The Rietveld refinement verified a dominating tetragonal P4mm phase with a minor P4/mbm phase, whereas electron density mapping indicated significant B-site-O hybridization and lattice deformation. The ceramics had diffuse phase dielectric behavior with a suppressed dielectric orthorhombic-tetragonal transition, and AC conductivity showed oxygen-vacancy-mediated hopping with a temperature-dependent shift from NSPT to CBH conduction. The ideal composition (x = 0.05) resulted in better ferroelectric characteristics (P r = 5.76 μC/cm2, P max = 9.20 μC/cm2), a maximum electrocaloric response (ΔT = 0.39 K, ΔT/ΔE = 1.30 × 10−7 Km/V), pyroelectric coefficient (p = 993∗10−4C·m−2·K−1), and maximum figure of merit FOMs F i , F v , F e , and F∗ e at only 30 kV/cm. These findings show that BNZ-modified KNLNT ceramics are attractive lead-free alternatives for low-field electric cooling refrigeration and pyroelectric applications. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Lead-free, multifunctional ceramics with excellent electrocaloric and pyroelectric performance at low electric fields are required for long-term solid-state cooling and energy harvesting applications. This work created (1-x) K 0.47 Na 0.47 Li 0.06 Nb 0.98 Ta 0.02 O 3 + (x) Bi 0.5 Na 0.5 ZrO 3 ceramics using a two-step low-temperature method to reduce alkali volatilization and increase densification. The Rietveld refinement verified a dominating tetragonal P4mm phase with a minor P4/mbm phase, whereas electron density mapping indicated significant B-site-O hybridization and lattice deformation. The ceramics had diffuse phase dielectric behavior with a suppressed dielectric orthorhombic-tetragonal transition, and AC conductivity showed oxygen-vacancy-mediated hopping with a temperature-dependent shift from NSPT to CBH conduction. The ideal composition (x = 0.05) resulted in better ferroelectric characteristics (P r = 5.76 μC/cm2, P max = 9.20 μC/cm2), a maximum electrocaloric response (ΔT = 0.39 K, ΔT/ΔE = 1.30 × 10−7 Km/V), pyroelectric coefficient (p = 993∗10−4C·m−2·K−1), and maximum figure of merit FOMs F i , F v , F e , and F∗ e at only 30 kV/cm. These findings show that BNZ-modified KNLNT ceramics are attractive lead-free alternatives for low-field electric cooling refrigeration and pyroelectric applications. [ABSTRACT FROM AUTHOR]
ISSN:02728842
DOI:10.1016/j.ceramint.2026.02.107