New Preparation Method of Low‐Temperature‐Sinterable Perovskite 0.9Pb(Mg_1/3Nb_2/3)O₃‐0.1PbTiO₃ Powder and Its Dielectric Properties

Abstract

A relaxor ferroelectric material, 0.9Pb(Mg 1/3 Nb 2/3 )O 3 -0.1PbTiO 3 (0.9PMN-0.1PT) with a pyrochlore-free phase, was prepared by using one-step calcination in the present study. The 0.9PMN-0.1PT powder with the pure perovskite phase was prepared successfully from a mixture of the PMN precursor and the crystalline PT by heating for 2 h at temperatures ≥750°C. The PMN precursor was synthesized by adding an aqueous Mg(NO 3 ) 2 solution, rather than MgO, to the alcoholic slurry of PbO and Nb 2 O 5 . The 0.9PMN-0.1PT powder sintered to >96% relative density via heat treatment for 2 h at temperatures of 900°-1200°C. The highest room-temperature dielectric constant ( rt ) was 24700 at 1 kHz for the samples that were sintered at 1100°C; however, the samples that were sintered at 900°C still had rt values of 22600 at 1 kHz.

Low-temperature single-step reactive sintering methods for lead magnesium niobate

“…Studies showed that the Mg 2+ reactivity and distribution was critical to the perovskite phase formation [24,25]. With this principle, the PMN pervoskite powder was prepared successfully via a single-step calcination by replacing MgO with Mg(NO 3 ) 2 [12].…”

“…1 -4 at.% of SrO doping would result in the low sintering temperature of 800 -900 -C [17]. Using the PMN powder made from Mg(NO 3 ) 2 mixing method, the sintering temperature was decreased to 900 -C [12]. Directly pressing the columbite phase (MgNb 2 O 6 ) and PbO into green bodies and then reactively sintering the green bodies reduced the total processing steps of PMN/PMN -PT ceramics into two steps of ball-millings, one step of calcination, and one step of sintering [18].…”

“…This method was widely adopted due to its relatively less stringent requirement to the raw materials and equipment. Later, many other methods were also found to be able to eliminate the formation of pyrochlore phase in powders, which include sol-gel methods [3][4][5][6], solution processes method [7 -9], coprecipitation method [10], soft mechanochemical pulverization method [11], Mg(NO 3 ) 2 mixing method [12], and coating method [13].…”

Preparations and characterizations of perovskite 0.80PMN–0.20PT ceramic by using a one-step calcination method

“…Swartz and Shrout [8] obtained PMN in high yield by using a columbite route, in which MgO and Nb 2 O 5 are first reacted to synthesize columbite phase (MgNb 2 O 6 ), followed by the reaction with PbO to synthesize perovskite phase. Several other processing methods have also been able to eliminate the formation of pyrochlore phase in powders, including sol-gel, solution processes, co-precipitation, soft mechanochemical pulverization, Mg(NO 3 ) 2 mixing, molten salt method, and thermal spray methods [9][10][11][12][13][14][15].…”

Low‐Temperature, Single Step, Reactive Sintering of Lead Magnesium Niobate Using Mg(OH)2‐Coated Nb2O5 Powders

“…This method was widely adopted in both the industry and the scientific research due to its relatively less stringent requirement to the raw materials and equipment. Several other processing methods have also been found that were able to eliminate the formation of pyrochlore phase in powders, including sol–gel, 3–6 solution processes, 7–9 co‐precipitation, 10 soft mechanochemical pulverization, 11 Mg(NO 3 ) 2 mixing, 12 and thermal spray methods 13 . A molten salt method has also been shown to be able to produce single‐phase perovskite PMN–PT powders 14 …”