我們研究了 Nd1-xNaxMnO3 (x = 0,0.1,0.167,0.25)的磁性和電性。
在x = 0的樣本中，觀測到負的淨磁強度(magnetization)，
這是非常有趣的結果。其他三個樣本,則顯現鐵磁性(FM)絕緣體的行為，同時也觀察到內在的不同性質的磁性特徵:在130 kOe的磁場下，
x = 0.1 的樣本展示出可觀的磁阻。在x = 0.16和x = 0.25的樣本中，當溫度接近250K時，具有電荷成序(charge ordering，CO)轉換。巨磁阻(CMR)效應可經由滲出區了解，同時也和較高磁場中的CO-FM有關。當磁場超過30 kOe時，可以觀測到絕緣性到金屬性，以及隨後在更低溫時，緊接著的金屬性到絕緣性轉換，且伴隨著熱遲滯。

以固態反應過程調配一系列塊狀複晶的 Nd1-xAgxMnO3 樣本，
其中的 x 在 0.1 和 0.5 之間。 樣本之結構，磁性和磁阻被(詳細地)研究。X 光繞射圖形顯示當 x = 0.1 時，樣本為單一之鈣鈦礦結構，當 x>0.167 時，樣本由一個鐵磁相的鈣鈦礦結構和兩個非磁性的相，Ag 與 Mn3O4 所組成。 增加 Nd1-xAgxMnO3 中 Ag 的成分，磁阻會增大。和 x = 0.1 的樣本相較，x = 0.5 的樣本明顯具有較大的低磁場磁阻值。增大的磁阻，與自旋極化電子在銀之細粒與具有鈣鈦礦結構顆粒的介面間，與自旋相關的碰撞有關。

The magnetic and electrical properties of Nd1−xNaxMnO3 (x = 0, 0.1, 0.167, 0.25) are studied. A negative net magnetization is observed in the un-daped sample(x = 0). The other three samples show a ferromagnetic (FM)-insulator behavior, and intrinsic inhomogeneous magnetic characteristics are observed. Under a field of 130 kOe, the sample with x = 0.1 exhibits a sizable magnetoresistance (MR). For the samples with x = 0.167 and 0.25, there are charge ordering (CO) transitions near 250 K. The colossal magnetoresistance (CMR) effect can be understood under a percolative regime and is related to the CO-FM transition in a larger magnetic field. When the applied field is more than 30 kOe, a field-induced insulator–metal and a following metal–insulator transition at a lower temperature are observed, accompanied by a thermal hysteresis.

A series of bulk polycrystalline Nd1-xAgxMnO3 samples were prepared by conventional solid-state reaction processing, for with x between 0.1 and 0.5. The structure, magnetism, and magnetoresistance (MR) of these samples are investigated. The X-ray diffraction patterns show that the x = 0.1 sample exhitits a single perovskite structure, while x 产 0.167, samples consist of a ferromagnetic perovskite phase and two nonmagnetic phases, Ag and Mn3O4. The MR of Nd1-xAgxMnO3 is enhanced by increasing the composition of Ag. Compared with the composition of x = 0.1, the x = 0.5 sample has a significantly larger value in the low-field MR. The enhanced low-field MR is related to the spin dependent scattering of spin-polarized electrons at the interfaces between the perovskite grains and silver granules.

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