Nghiên cứu chuyển pha, trật tự từ và hiệu ứng từ nhiệt trong các hệ vật liệu perovskite nền la0,7a0,3mno3 (a = ca, sr, ba

BỘ GIÁO DỤC VÀ ĐÀO TẠO VIỆN HÀN LÂM KHOA HỌC VÀ CÔNG NGHỆ VIỆT NAM HỌC VIỆN KHOA HỌC VÀ CÔNG NGHỆ - ĐINH CHÍ LINH NGHIÊN CỨU CHUYỂN PHA, TRẬT TỰ TỪ VÀ HIỆU ỨNG TỪ NHIỆT TRONG CÁC HỆ VẬT LIỆU PEROVSKITE NỀN La0,7A0,3MnO3 (A = Ca, Sr, Ba) LUẬN ÁN TIẾN SĨ KHOA HỌC VẬT LIỆU HÀ NỘI – 2021 VIỆN HÀN LÂM KHOA HỌC VÀ CÔNG NGHỆ VIỆT NAM HỌC VIỆN KHOA HỌC VÀ CÔNG NGHỆ … … …***… … … ĐINH CHÍ LINH NGHIÊN CỨU CHUYỂN PHA, TRẬT TỰ TỪ VÀ HIỆU ỨNG TỪ NHIỆT TRONG CÁC HỆ VẬT LIỆU PEROVSKITE NỀN La0,7A0,3MnO3 (A = Ca, Sr, Ba) LUẬN ÁN TIẾN SĨ KHOA HỌC VẬT LIỆU Chuyên ngành: Vật liệu điện tử Mã số: 9.44.01.23 NGƯỜI HƯỚNG DẪN KHOA HỌC: PGS.TS Trần Đăng Thành PGS.TS Lê Viết Báu Hà Nội – 2021 i LỜI CAM ĐOAN Tôi xin cam đoan cơng trình nghiên cứu riêng hướng dẫn PGS.TS Trần Đăng Thành PGS.TS Lê Viết Báu hợp tác đồng nghiệp Các số liệu kết luận án trung thực chưa công bố luận án khác Tác giả luận án Đinh Chí Linh ii LỜI CÁM ƠN Lời đầu tiên, tơi xin bày tỏ lịng kính trọng biết ơn sâu sắc đến PGS.TS Trần Đăng Thành PGS.TS Lê Viết Báu, người thầy trực tiếp tận tình hướng dẫn, giúp đỡ tạo điều kiện thuận lợi cho suốt thời gian thực luận án Ngoài việc hướng dẫn tận tâm mặt khoa học, thầy cịn ln quan tâm, động viên khích lệ tơi gặp khó khăn sống Tơi chân thành cám ơn giúp đỡ tạo điều kiện thuận lợi cho học tập nghiên cứu Học viện Khoa học Công nghệ, Viện Khoa học vật liệu, Viện Hàn lâm Khoa học Công nghệ Việt Nam Tôi xin chân thành cám ơn lãnh đạo cấp Sở GD&ĐT Phú Thọ, đặc biệt xin gửi lời tri ân đến anh Nguyễn Văn Hùng-Hiệu trưởng Trường THPT Thạch Kiệt- tạo điều kiện thời gian hỗ trợ tài cho tơi suốt tháng năm học tập qua Tôi xin cám ơn định hướng nghiên cứu giúp đỡ nhiệt tình GS.TS Nguyễn Huy Dân thời gian đầu suốt q trình tơi thực luận án Được gặp gỡ thầy bước ngoặt to lớn sống nghiệp Tôi xin cám ơn anh chị em làm việc Phòng Thí nghiệm trọng điểm Vật liệu Linh kiện Điện tử: TS Nguyễn Hải Yến, TS Phạm Thị Thanh, TS Nguyễn Mẫu Lâm, TS Nguyễn Hữu Đức, TS Đào Sơn Lâm, NCS Nguyễn Văn Dương, NCS Nguyễn Hoàng Hà, NCS Nguyễn Thị Dung Những trao đổi chuyên môn sâu sắc, kinh nghiệm nghiên cứu hữu ích giúp đỡ vô tư anh chị bạn phần đóng góp to lớn giúp tơi hồn thành luận án Tôi vô biết ơn giúp đỡ nhiệt tình hào phóng giáo sư S C Yu, Đại học Quốc gia Chungbuck, Hàn Quốc Cơ hội thực tập tại Hàn Quốc mà Giáo sư đem đến cho phần quan trọng giúp đạt thành tựu ngày hôm Hơn nữa, khoảng thời gian sống làm việc cho tơi có nhìn rộng mở người sống Luận án thực Phịng Thí nghiệm trọng điểm Vật liệu Linh kiện Điện tử - Viện Khoa học vật liệu Luận án nhận hỗ trợ kinh phí từ đề tài nghiên cứu cứu Quỹ Phát triển khoa học công nghệ Quốc gia (NAFOSTED) mã số 103.02-2012.57; 103.02-2015.06 103.02-2019.42 Sau cùng, muốn gửi tới tất người thân gia đình bạn bè lời cảm ơn chân thành Sự tin tưởng giúp đỡ mặt gia đình bạn bè chỗ dựa vững nguồn lực to lớn cho thực thành công luận án iii MỤC LỤC LỜI CAM ĐOAN i LỜI CÁM ƠN ii MỤC LỤC iii DANH MỤC CÁC KÝ HIỆU, CÁC CHỮ VIẾT TẮT vi DANH MỤC CÁC BẢNG x DANH MỤC CÁC HÌNH VẼ VÀ ĐỒ THỊ xi MỞ ĐẦU CHƯƠNG HIỆU ỨNG TỪ NHIỆT VÀ VẬT LIỆU PEROVSKITE MANGANITE 1.1 Hiệu ứng từ nhiệt 1.1.1 Cơ sở nhiệt động lực học đại lượng đặc trưng hiệu ứng từ nhiệt 1.1.2 Các phương pháp xác định độ lớn hiệu ứng từ nhiệt 10 1.1.2.1 Phương pháp trực tiếp 10 1.1.2.2 Phương pháp gián tiếp 11 1.1.3 Đường cong rút gọn phụ thuộc từ trường độ biến thiên entropy từ 14 1.1.3.1 Đường cong rút gọn độ biến thiên entropy từ 14 1.1.3.2 Sự phụ thuộc từ trường độ biến thiên entropy từ 16 1.1.4 Các hệ vật liệu từ nhiệt hợp kim tiềm cho ứng dụng làm lạnh từ vùng nhiệt độ phòng 18 1.1.4.1 Kim loại Gd hợp kim Gd-Si-Ge .18 1.1.4.2 Hợp kim La-Fe-Si 19 1.1.4.3 Hợp kim kim loại Mn .20 1.2 Vật liệu perovskite manganite 21 1.2.1 Cấu trúc perovskite 21 1.2.2 Sự tách mức lượng tượng biến dạng mạng 22 1.2.3 Các tương tác trao đổi .24 1.2.3.1 Tương tác siêu trao đổi 24 1.2.3.2 Tương tác trao đổi kép 26 1.2.4 Hiệu ứng từ nhiệt vật liệu perovskite manganite 27 1.2.4.1 Hệ La1-xMxMnO3 (M = Na, K Ag) 27 1.2.4.2 Hệ La1-xMxMnO3 (M = Ca, Sr Ba) 28 1.2.4.3 So sánh MCE manganite với vật liệu từ nhiệt hợp kim 31 Kết luận chương 33 iv CHƯƠNG HIỆN TƯỢNG TỚI HẠN TRONG CHUYỂN PHA TỪ 34 2.1 Định nghĩa phân loại chuyển pha 35 2.1.1 Định nghĩa chuyển pha 35 2.1.2 Phân loại chuyển pha 36 2.1.3 Một số phương pháp xác định loại chuyển pha vật liệu từ .38 2.1.3.1 Xác định loại chuyển pha theo tiêu chí Banerjee .38 2.1.3.2 Xác định loại chuyển pha theo đường cong rút gọn độ biến thiên entropy từ 39 2.1.3.3 Xác định loại chuyển pha theo số mũ phụ thuộc từ trường độ biến thiên entropy từ 40 2.2 Một số mơ hình sắt từ lớp phổ quát phổ biến 41 2.2.1 Mô hình sắt từ 41 2.2.1.1 Mơ hình trường trung bình 41 2.2.1.2 Mơ hình Ising .42 2.2.1.3 Mô hình Heisenberg .43 2.2.2 Số mũ tới hạn Lý thuyết Landau chuyển pha bậc hai 44 2.2.3 Giới hạn trường trung bình lớp phổ quát phổ biến 46 2.2.4 Một số phương pháp xác định số mũ tới hạn chuyển pha từ 47 2.2.4.1 Phương pháp thay đổi đường Arrott .47 2.2.4.2 Phương pháp Kouvel-Fisher 49 2.2.4.3 Xác định số mũ tới hạn β từ số liệu độ biến thiên entropy từ 50 2.2.5 Biểu tới hạn manganite La0,7A0,3MnO3 (A = Ca, Sr, Ba) 50 Kết luận chương 53 CHƯƠNG THỰC NGHIỆM .54 3.1 Phương pháp chế tạo vật liệu 54 3.1.1 Phương pháp phản ứng pha rắn .55 3.1.2 Phương pháp nghiền lượng cao 56 3.2 Xác định cấu trúc nhiễu xạ tia X mẫu bột 58 3.3 Xác định từ độ hệ từ kế mẫu rung 59 Kết luận chương 61 CHƯƠNG CHUYỂN PHA VÀ HIỆU ỨNG TỪ NHIỆT CỦA HỆ VẬT LIỆU La0,7-xNaxCa0,3MnO3 .61 4.1 Cấu trúc tinh thể hệ La0,7-xNaxCa0,3MnO3 (x = 0; 0,05 0,1) 63 4.2 Tính chất từ hệ La0,7-xNaxCa0,3MnO3 (x = 0; 0,05 0,1) 66 4.3 Chuyển pha hiệu ứng từ nhiệt hệ La0,7-xNaxCa0,3MnO3 (x = 0; 0,05 0,1) 68 Kết luận chương 78 v CHƯƠNG CHUYỂN PHA VÀ HIỆU ỨNG TỪ NHIỆT CỦA HỆ VẬT LIỆU La0,7Ca0,3-xAxMnO3 (A = Sr, Ba) 79 5.1 Chuyển pha hiệu ứng từ nhiệt hệ La0,7Ca0,3-xAxMnO3 (A = Sr, Ba) 80 5.1.1 Cấu trúc tinh thể hệ La0,7Ca0,3-xAxMnO3 (A = Sr, Ba; x = 0; 0,15; 0,03) 80 5.1.2 Chuyển pha hệ La0,7Ca0,3-xAxMnO3 (A = Sr, Ba; x = 0; 0,15; 0,03) .82 5.1.3 Hiệu ứng từ nhiệt hệ La0,7Ca0,3-xAxMnO3 (A = Sr, Ba; x = 0; 0,15; 0,03) 88 5.2 Chuyển pha hiệu ứng từ nhiệt vật liệu nano tinh thể La0,7Ca0,275Ba0,025MnO3 91 5.2.1 Cấu trúc hệ nano tinh thể La0,7Ca0,275Ba0,025MnO3 (38 - 200 nm) 92 5.2.2 Tính chất từ chuyển pha hệ nano tinh thể La0,7Ca0,275Ba0,025MnO3 (38 200 nm) .95 5.2.3 Hiệu ứng từ nhiệt hệ nano tinh thể La0,7Ca0,275Ba0,025MnO3 (38 - 200 nm) 100 Kết luận chương 103 CHƯƠNG BIỂU HIỆN TỚI HẠN CỦA HỆ VẬT LIỆU La0,7A0,3MnO3 (A = Ca, Sr, Ba) 104 6.1 Biểu tới hạn hệ vật liệu La0,7Ca0,3-xAxMnO3 (A = Sr, Ba, x = 0,15; 0,3) 105 6.1.1 Các tham số tới hạn hệ vật liệu La0,7Ca0,3-xAxMnO3 (A = Sr, Ba, x = 0,15; 0,3) 105 6.1.2 Trật tự tương tác sắt từ hệ vật liệu La0,7Ca0,3-xAxMnO3 (A = Sr, Ba, x = 0,15; 0,3) 114 6.2 Biểu tới hạn hệ vật liệu La0,7Sr0,3Mn1−xCoxO3 (x = 0-1) .117 6.2.1 Chuyển pha hệ vật liệu La0,7Sr0,3Mn1−xCoxO3 (x = 0-1) 118 6.2.2 Trật tự tương tác sắt từ hệ vật liệu La0,7Sr0,3Mn1−xCoxO3 (x = 0-1) .121 Kết luận chương 125 KẾT LUẬN CHUNG 126 DANH MỤC CƠNG TRÌNH LIÊN QUAN ĐẾN LUẬN ÁN CỦA TÁC GIẢ 128 TÀI LIỆU THAM KHẢO 129 vi DANH MỤC CÁC KÝ HIỆU, CÁC CHỮ VIẾT TẮT Danh mục ký hiệu Ký hiệu Ý nghĩa β Số mũ tới hạn liên quan đến MS β eff Số mũ tới hạn hiệu dụng liên quan đến MS γ Số mũ tới hạn liên quan đến 0-1 γ eff Số mũ tới hạn hiệu dụng liên quan đến 0-1 δ Số mũ tới hạn liên quan đến Ms nhiệt độ TC δTFWHM Khoảng/vùng nhiệt độ làm việc λ Bước sóng tia X λm Μeff Hằng số trường phân tử ξ Ứng suất σ2 Phương sai bán kính ion trung bình τ Thừa số dung hạn  Độ cảm từ thuận từ 0 Độ cảm từ ban đầu |∆SM|, |∆SMax| Độ biến thiên entropy từ cực đại , ∆H Bán kính ion trung bình vị trí A, B cấu trúc perovskite ABO3 Độ biến thiên từ trường ∆Sm Biến thiên entropy từ a, b, c Các số mạng C Hằng số Curie D Số chiều khơng gian d Kích thước hạt tinh thể dcri Kích thước tới hạn dhkl Khoảng cách hai mặt phẳng mạng tinh thể gần Eex Năng lượng tương tác trao đổi ɛ, θ Các nhiệt độ rút gọn G Năng lượng tự Momen từ hiệu dụng vii g Thừa số Lande H Từ trường Ha Từ trường Hc Lực kháng từ Heff Từ trường hiệu dụng hkl Bộ số Miller Hm Trường phân tử J Tích phân trao đổi kB Hằng số Boltzmann M Từ độ m Số thành phần véc tơ spin MS Từ độ tự phát n Số mũ phụ thuộc từ trường độ biến thiên entropy từ N Số mũ phụ thuộc từ trường khả làm lạnh tương đối S Tổng entropy Sel Entropy điện tử Slat Entropy mạng Sm Entropy từ T Nhiệt độ TC Nhiệt độ Curie Tpeak Nhiệt độ cho độ biến thiên entropy từ cực đại Tr1, Tr2 Các nhiệt độ tham chiếu V Thể tích sở W Bề rộng dải dẫn Danh mục chữ viết tắt Chữ viết tắt Tiếng Anh Tiếng Việt AFM Antiferromagnetic Phản sắt từ CAFM Cant Antiferromagnetic Phản sắt từ nghiêng CMR Colossal magnetoresistance Hiệu ứng từ trở khổng lồ CO Charge order Trật tự điện tích viii đ.v.t.y Arbitrary units Đơn vị tùy ý DE Double exchange Tương tác trao đổi kép FC Field cool Làm lạnh có từ trường FM Ferromagnetic Sắt từ FOPT First order phase transition Chuyển pha bậc GMCE Giant magnetocaloric effect Hiệu ứng từ nhiệt lớn J-T Jahn – Teller Jahn – Teller K-F Kouvel - Fisher Kouvel – Fisher LB La0,7Ba0,3MnO3 La0,7Ba0,3MnO3 LCB La0,7Ca0,15Ba0,15MnO3 La0,7Ca0,15Ba0,15MnO3 LCBMO La0,7Ca0,3-xBaxMnO3 La0,7Ca0,3-xBaxMnO3 LCMO/LC La0,7Ca0,3MnO3 La0,7Ca0,3MnO3 LCS La0,7Ca0,15Sr0,15MnO3 La0,7Ca0,15Sr0,15MnO3 LCSMO La0,7Ca0,3-xSrxMnO3 La0,7Ca0,3-xSrxMnO3 LS La0,7Sr0,3MnO3 La0,7Sr0,3MnO3 LSMCO La0,7Sr0,3Mn1−xCoxO3 La0,7Sr0,3Mn1−xCoxO3 MAP Modify Arrott plots Thay đổi đường Arrott MCE Magnetocaloric effect Hiệu ứng từ nhiệt MCM Magnetocaloric material Vật liệu từ nhiệt MFT Mean field theory Trường trung bình MPMS Magnetic properties measurement system Hệ đo tính chất từ MR Magnetic refrigeration Công nghệ làm lạnh từ trường NCNLC High energy millling Nghiền lượng cao OO Order orbital Trật tự quỹ đạo PM Paramagnetic Thuận từ PƯPR Solid state reaction Phản ứng pha rắn RC Refrigerant capacity Khả làm lạnh RCP Relative cooling power Khả làm lạnh tương đối RT Room temperature 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VÀ CÔNG NGHỆ VIỆT NAM HỌC VIỆN KHOA HỌC VÀ CÔNG NGHỆ … … …***… … … ĐINH CHÍ LINH NGHIÊN CỨU CHUYỂN PHA, TRẬT TỰ TỪ VÀ HIỆU ỨNG TỪ NHIỆT TRONG CÁC HỆ VẬT LIỆU PEROVSKITE NỀN La0,7A0,3MnO3 (A =. .. CHƯƠNG CHUYỂN PHA VÀ HIỆU ỨNG TỪ NHIỆT CỦA HỆ VẬT LIỆU La0,7Ca0,3-xAxMnO3 (A = Sr, Ba) 79 5.1 Chuyển pha hiệu ứng từ nhiệt hệ La0,7Ca0,3-xAxMnO3 (A = Sr, Ba) 80 5.1.1 Cấu trúc tinh thể hệ. .. La0,7Ca0,3-xAxMnO3 (A = Sr, Ba; x = 0; 0,15; 0,03) 80 5.1.2 Chuyển pha hệ La0,7Ca0,3-xAxMnO3 (A = Sr, Ba; x = 0; 0,15; 0,03) .82 5.1.3 Hiệu ứng từ nhiệt hệ La0,7Ca0,3-xAxMnO3 (A = Sr, Ba; x = 0; 0,15;