Blar i Institutt for materialteknologi på forfatter "Walker, Julian Bradley"
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The effect of cation size on structure and properties of Ba-based tetragonal tungsten bronzes Ba4M2Nb10O30 (M = Na, K or Rb) and Ba4M2Nb8Ti2O30 (M = Ca or Sr)†
Løndal, Nora Statle; Williamson, Benjamin Albert Dobson; Walker, Julian Bradley; Einarsrud, Mari-Ann; Grande, Tor (Peer reviewed; Journal article, 2024)The second largest family of oxide ferroelectrics, after perovskites, are the tetragonal tungsten bronzes (TTB) with the general formula A24A12C4B12B28O30. Cation disorder in TTBs is known to occur if the size difference ... -
Electronic Structure and Surface Chemistry of Hexagonal Boron Nitride on HOPG and Nickel Substrates
Småbråten, Didrik Rene; Nylund, Inger-Emma; Marshall, Kenneth; Walker, Julian Bradley; Benelmekki, Maria; Einarsrud, Mari-Ann; Kioseoglou, Joseph; Selbach, Sverre Magnus (Peer reviewed; Journal article, 2023)The effect of point defects and interactions with the substrate are shown by density functional theory calculations to be of significant importance for the structure and functional properties of hexagonal boron nitride ... -
Empowering CO2 Eco-Refrigeration with Colossal Breathing-Caloric-Like Effects in MOF-508b
Gelpi, Maria; Garcia-Ben, Javier; Rodríguez-Hermida, Sabina; López-Beceiro, Jorge; Artiaga, Ramón; Baaliña, Álvaro; Romero-Gomez, Manuel; Romero-Gómez, Javier; Zaragoza, Sonia; Beceiro, Jorge Salgado; Walker, Julian Bradley; McMonagle, Charles James; Castro-Garcia, Socorro; Andújar, Manuel Sánchez; Señarís-Rodríguez, María Antonia; Bermúdez-García, Juan Manuel (Peer reviewed; Journal article, 2023)Today, ≈20% of the electric consumption is devoted to refrigeration; while, ≈50% of the final energy is dedicated to heating applications. In this scenario, many cooling devices and heat-pumps are transitioning toward the ... -
On the Solubility of Bi in Tetragonal Tungsten Bronzes
Zeiger, Caren Regine; Williamson, Benjamin Albert Dobson; Walker, Julian Bradley; Einarsrud, Mari-Ann; Grande, Tor (Peer reviewed; Journal article, 2024)Ferroelectric Pb5Nb10O30 (PN) tetragonal tungsten bronze (TTB) forms solid solutions that exhibit morphotropic phase boundaries (MPBs). Successful replacement of PN with TTBs containing Bi could advance lead-free TTB MPBs. ... -
Thermal expansion of SrxBa1−xNb2O6 across and above the ferroelectric phase transition
Pedersen, Viviann Hole; Chavez Panduro, Elvia Anabela; Hua, Weicheng; Michaelsen, Marcus Grand; Chernyshov, Dmitry; Walker, Julian Bradley; Grande, Tor; Einarsrud, Mari-Ann (Peer reviewed; Journal article, 2024)Lead-free SrxBa1−xNb2O6(SBN) is of interest due to flexible chemistry, ferroelectric behavior, and electro-optic properties. The thermal expansion coefficient for SBN is reported only for compositions x = 0.35–0.59 and ...